11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * linux/fs/namei.c 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright (C) 1991, 1992 Linus Torvalds 51da177e4SLinus Torvalds */ 61da177e4SLinus Torvalds 71da177e4SLinus Torvalds /* 81da177e4SLinus Torvalds * Some corrections by tytso. 91da177e4SLinus Torvalds */ 101da177e4SLinus Torvalds 111da177e4SLinus Torvalds /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname 121da177e4SLinus Torvalds * lookup logic. 131da177e4SLinus Torvalds */ 141da177e4SLinus Torvalds /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture. 151da177e4SLinus Torvalds */ 161da177e4SLinus Torvalds 171da177e4SLinus Torvalds #include <linux/init.h> 18630d9c47SPaul Gortmaker #include <linux/export.h> 1944696908SDavid S. Miller #include <linux/kernel.h> 201da177e4SLinus Torvalds #include <linux/slab.h> 211da177e4SLinus Torvalds #include <linux/fs.h> 221da177e4SLinus Torvalds #include <linux/namei.h> 231da177e4SLinus Torvalds #include <linux/pagemap.h> 240eeca283SRobert Love #include <linux/fsnotify.h> 251da177e4SLinus Torvalds #include <linux/personality.h> 261da177e4SLinus Torvalds #include <linux/security.h> 276146f0d5SMimi Zohar #include <linux/ima.h> 281da177e4SLinus Torvalds #include <linux/syscalls.h> 291da177e4SLinus Torvalds #include <linux/mount.h> 301da177e4SLinus Torvalds #include <linux/audit.h> 3116f7e0feSRandy Dunlap #include <linux/capability.h> 32834f2a4aSTrond Myklebust #include <linux/file.h> 335590ff0dSUlrich Drepper #include <linux/fcntl.h> 3408ce5f16SSerge E. Hallyn #include <linux/device_cgroup.h> 355ad4e53bSAl Viro #include <linux/fs_struct.h> 36e77819e5SLinus Torvalds #include <linux/posix_acl.h> 3799d263d4SLinus Torvalds #include <linux/hash.h> 381da177e4SLinus Torvalds #include <asm/uaccess.h> 391da177e4SLinus Torvalds 40e81e3f4dSEric Paris #include "internal.h" 41c7105365SAl Viro #include "mount.h" 42e81e3f4dSEric Paris 431da177e4SLinus Torvalds /* [Feb-1997 T. Schoebel-Theuer] 441da177e4SLinus Torvalds * Fundamental changes in the pathname lookup mechanisms (namei) 451da177e4SLinus Torvalds * were necessary because of omirr. The reason is that omirr needs 461da177e4SLinus Torvalds * to know the _real_ pathname, not the user-supplied one, in case 471da177e4SLinus Torvalds * of symlinks (and also when transname replacements occur). 481da177e4SLinus Torvalds * 491da177e4SLinus Torvalds * The new code replaces the old recursive symlink resolution with 501da177e4SLinus Torvalds * an iterative one (in case of non-nested symlink chains). It does 511da177e4SLinus Torvalds * this with calls to <fs>_follow_link(). 521da177e4SLinus Torvalds * As a side effect, dir_namei(), _namei() and follow_link() are now 531da177e4SLinus Torvalds * replaced with a single function lookup_dentry() that can handle all 541da177e4SLinus Torvalds * the special cases of the former code. 551da177e4SLinus Torvalds * 561da177e4SLinus Torvalds * With the new dcache, the pathname is stored at each inode, at least as 571da177e4SLinus Torvalds * long as the refcount of the inode is positive. As a side effect, the 581da177e4SLinus Torvalds * size of the dcache depends on the inode cache and thus is dynamic. 591da177e4SLinus Torvalds * 601da177e4SLinus Torvalds * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink 611da177e4SLinus Torvalds * resolution to correspond with current state of the code. 621da177e4SLinus Torvalds * 631da177e4SLinus Torvalds * Note that the symlink resolution is not *completely* iterative. 641da177e4SLinus Torvalds * There is still a significant amount of tail- and mid- recursion in 651da177e4SLinus Torvalds * the algorithm. Also, note that <fs>_readlink() is not used in 661da177e4SLinus Torvalds * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink() 671da177e4SLinus Torvalds * may return different results than <fs>_follow_link(). Many virtual 681da177e4SLinus Torvalds * filesystems (including /proc) exhibit this behavior. 691da177e4SLinus Torvalds */ 701da177e4SLinus Torvalds 711da177e4SLinus Torvalds /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation: 721da177e4SLinus Torvalds * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL 731da177e4SLinus Torvalds * and the name already exists in form of a symlink, try to create the new 741da177e4SLinus Torvalds * name indicated by the symlink. The old code always complained that the 751da177e4SLinus Torvalds * name already exists, due to not following the symlink even if its target 761da177e4SLinus Torvalds * is nonexistent. The new semantics affects also mknod() and link() when 7725985edcSLucas De Marchi * the name is a symlink pointing to a non-existent name. 781da177e4SLinus Torvalds * 791da177e4SLinus Torvalds * I don't know which semantics is the right one, since I have no access 801da177e4SLinus Torvalds * to standards. But I found by trial that HP-UX 9.0 has the full "new" 811da177e4SLinus Torvalds * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the 821da177e4SLinus Torvalds * "old" one. Personally, I think the new semantics is much more logical. 831da177e4SLinus Torvalds * Note that "ln old new" where "new" is a symlink pointing to a non-existing 841da177e4SLinus Torvalds * file does succeed in both HP-UX and SunOs, but not in Solaris 851da177e4SLinus Torvalds * and in the old Linux semantics. 861da177e4SLinus Torvalds */ 871da177e4SLinus Torvalds 881da177e4SLinus Torvalds /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink 891da177e4SLinus Torvalds * semantics. See the comments in "open_namei" and "do_link" below. 901da177e4SLinus Torvalds * 911da177e4SLinus Torvalds * [10-Sep-98 Alan Modra] Another symlink change. 921da177e4SLinus Torvalds */ 931da177e4SLinus Torvalds 941da177e4SLinus Torvalds /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks: 951da177e4SLinus Torvalds * inside the path - always follow. 961da177e4SLinus Torvalds * in the last component in creation/removal/renaming - never follow. 971da177e4SLinus Torvalds * if LOOKUP_FOLLOW passed - follow. 981da177e4SLinus Torvalds * if the pathname has trailing slashes - follow. 991da177e4SLinus Torvalds * otherwise - don't follow. 1001da177e4SLinus Torvalds * (applied in that order). 1011da177e4SLinus Torvalds * 1021da177e4SLinus Torvalds * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT 1031da177e4SLinus Torvalds * restored for 2.4. This is the last surviving part of old 4.2BSD bug. 1041da177e4SLinus Torvalds * During the 2.4 we need to fix the userland stuff depending on it - 1051da177e4SLinus Torvalds * hopefully we will be able to get rid of that wart in 2.5. So far only 1061da177e4SLinus Torvalds * XEmacs seems to be relying on it... 1071da177e4SLinus Torvalds */ 1081da177e4SLinus Torvalds /* 1091da177e4SLinus Torvalds * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland) 110a11f3a05SArjan van de Ven * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives 1111da177e4SLinus Torvalds * any extra contention... 1121da177e4SLinus Torvalds */ 1131da177e4SLinus Torvalds 1141da177e4SLinus Torvalds /* In order to reduce some races, while at the same time doing additional 1151da177e4SLinus Torvalds * checking and hopefully speeding things up, we copy filenames to the 1161da177e4SLinus Torvalds * kernel data space before using them.. 1171da177e4SLinus Torvalds * 1181da177e4SLinus Torvalds * POSIX.1 2.4: an empty pathname is invalid (ENOENT). 1191da177e4SLinus Torvalds * PATH_MAX includes the nul terminator --RR. 1201da177e4SLinus Torvalds */ 1217950e385SJeff Layton 122fd2f7cb5SAl Viro #define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname)) 12391a27b2aSJeff Layton 12451f39a1fSDavid Drysdale struct filename * 12591a27b2aSJeff Layton getname_flags(const char __user *filename, int flags, int *empty) 12691a27b2aSJeff Layton { 12794b5d262SAl Viro struct filename *result; 1287950e385SJeff Layton char *kname; 12994b5d262SAl Viro int len; 1301da177e4SLinus Torvalds 1317ac86265SJeff Layton result = audit_reusename(filename); 1327ac86265SJeff Layton if (result) 1337ac86265SJeff Layton return result; 1347ac86265SJeff Layton 1357950e385SJeff Layton result = __getname(); 1363f9f0aa6SLinus Torvalds if (unlikely(!result)) 1374043cde8SEric Paris return ERR_PTR(-ENOMEM); 1381da177e4SLinus Torvalds 1397950e385SJeff Layton /* 1407950e385SJeff Layton * First, try to embed the struct filename inside the names_cache 1417950e385SJeff Layton * allocation 1427950e385SJeff Layton */ 143fd2f7cb5SAl Viro kname = (char *)result->iname; 14491a27b2aSJeff Layton result->name = kname; 1457950e385SJeff Layton 14694b5d262SAl Viro len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX); 14791a27b2aSJeff Layton if (unlikely(len < 0)) { 14894b5d262SAl Viro __putname(result); 14994b5d262SAl Viro return ERR_PTR(len); 15091a27b2aSJeff Layton } 1513f9f0aa6SLinus Torvalds 1527950e385SJeff Layton /* 1537950e385SJeff Layton * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a 1547950e385SJeff Layton * separate struct filename so we can dedicate the entire 1557950e385SJeff Layton * names_cache allocation for the pathname, and re-do the copy from 1567950e385SJeff Layton * userland. 1577950e385SJeff Layton */ 15894b5d262SAl Viro if (unlikely(len == EMBEDDED_NAME_MAX)) { 159fd2f7cb5SAl Viro const size_t size = offsetof(struct filename, iname[1]); 1607950e385SJeff Layton kname = (char *)result; 1617950e385SJeff Layton 162fd2f7cb5SAl Viro /* 163fd2f7cb5SAl Viro * size is chosen that way we to guarantee that 164fd2f7cb5SAl Viro * result->iname[0] is within the same object and that 165fd2f7cb5SAl Viro * kname can't be equal to result->iname, no matter what. 166fd2f7cb5SAl Viro */ 167fd2f7cb5SAl Viro result = kzalloc(size, GFP_KERNEL); 16894b5d262SAl Viro if (unlikely(!result)) { 16994b5d262SAl Viro __putname(kname); 17094b5d262SAl Viro return ERR_PTR(-ENOMEM); 1717950e385SJeff Layton } 1727950e385SJeff Layton result->name = kname; 17394b5d262SAl Viro len = strncpy_from_user(kname, filename, PATH_MAX); 17494b5d262SAl Viro if (unlikely(len < 0)) { 17594b5d262SAl Viro __putname(kname); 17694b5d262SAl Viro kfree(result); 17794b5d262SAl Viro return ERR_PTR(len); 17894b5d262SAl Viro } 17994b5d262SAl Viro if (unlikely(len == PATH_MAX)) { 18094b5d262SAl Viro __putname(kname); 18194b5d262SAl Viro kfree(result); 18294b5d262SAl Viro return ERR_PTR(-ENAMETOOLONG); 18394b5d262SAl Viro } 1847950e385SJeff Layton } 1857950e385SJeff Layton 18694b5d262SAl Viro result->refcnt = 1; 1873f9f0aa6SLinus Torvalds /* The empty path is special. */ 1883f9f0aa6SLinus Torvalds if (unlikely(!len)) { 1893f9f0aa6SLinus Torvalds if (empty) 1901fa1e7f6SAndy Whitcroft *empty = 1; 19194b5d262SAl Viro if (!(flags & LOOKUP_EMPTY)) { 19294b5d262SAl Viro putname(result); 19394b5d262SAl Viro return ERR_PTR(-ENOENT); 1941da177e4SLinus Torvalds } 19594b5d262SAl Viro } 1967950e385SJeff Layton 1977950e385SJeff Layton result->uptr = filename; 198c4ad8f98SLinus Torvalds result->aname = NULL; 1991da177e4SLinus Torvalds audit_getname(result); 2001da177e4SLinus Torvalds return result; 2013f9f0aa6SLinus Torvalds } 2023f9f0aa6SLinus Torvalds 20391a27b2aSJeff Layton struct filename * 20491a27b2aSJeff Layton getname(const char __user * filename) 205f52e0c11SAl Viro { 206f7493e5dSLinus Torvalds return getname_flags(filename, 0, NULL); 207f52e0c11SAl Viro } 208f52e0c11SAl Viro 209c4ad8f98SLinus Torvalds struct filename * 210c4ad8f98SLinus Torvalds getname_kernel(const char * filename) 211c4ad8f98SLinus Torvalds { 212c4ad8f98SLinus Torvalds struct filename *result; 21308518549SPaul Moore int len = strlen(filename) + 1; 214c4ad8f98SLinus Torvalds 215c4ad8f98SLinus Torvalds result = __getname(); 216c4ad8f98SLinus Torvalds if (unlikely(!result)) 217c4ad8f98SLinus Torvalds return ERR_PTR(-ENOMEM); 218c4ad8f98SLinus Torvalds 21908518549SPaul Moore if (len <= EMBEDDED_NAME_MAX) { 220fd2f7cb5SAl Viro result->name = (char *)result->iname; 22108518549SPaul Moore } else if (len <= PATH_MAX) { 22208518549SPaul Moore struct filename *tmp; 22308518549SPaul Moore 22408518549SPaul Moore tmp = kmalloc(sizeof(*tmp), GFP_KERNEL); 22508518549SPaul Moore if (unlikely(!tmp)) { 22608518549SPaul Moore __putname(result); 22708518549SPaul Moore return ERR_PTR(-ENOMEM); 22808518549SPaul Moore } 22908518549SPaul Moore tmp->name = (char *)result; 23008518549SPaul Moore result = tmp; 23108518549SPaul Moore } else { 23208518549SPaul Moore __putname(result); 23308518549SPaul Moore return ERR_PTR(-ENAMETOOLONG); 23408518549SPaul Moore } 23508518549SPaul Moore memcpy((char *)result->name, filename, len); 236c4ad8f98SLinus Torvalds result->uptr = NULL; 237c4ad8f98SLinus Torvalds result->aname = NULL; 23855422d0bSPaul Moore result->refcnt = 1; 239fd3522fdSPaul Moore audit_getname(result); 240c4ad8f98SLinus Torvalds 241c4ad8f98SLinus Torvalds return result; 242c4ad8f98SLinus Torvalds } 243c4ad8f98SLinus Torvalds 24491a27b2aSJeff Layton void putname(struct filename *name) 2451da177e4SLinus Torvalds { 24655422d0bSPaul Moore BUG_ON(name->refcnt <= 0); 24755422d0bSPaul Moore 24855422d0bSPaul Moore if (--name->refcnt > 0) 24955422d0bSPaul Moore return; 25055422d0bSPaul Moore 251fd2f7cb5SAl Viro if (name->name != name->iname) { 25255422d0bSPaul Moore __putname(name->name); 25355422d0bSPaul Moore kfree(name); 25455422d0bSPaul Moore } else 25555422d0bSPaul Moore __putname(name); 2561da177e4SLinus Torvalds } 2571da177e4SLinus Torvalds 258e77819e5SLinus Torvalds static int check_acl(struct inode *inode, int mask) 259e77819e5SLinus Torvalds { 26084635d68SLinus Torvalds #ifdef CONFIG_FS_POSIX_ACL 261e77819e5SLinus Torvalds struct posix_acl *acl; 262e77819e5SLinus Torvalds 263e77819e5SLinus Torvalds if (mask & MAY_NOT_BLOCK) { 2643567866bSAl Viro acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS); 2653567866bSAl Viro if (!acl) 266e77819e5SLinus Torvalds return -EAGAIN; 2673567866bSAl Viro /* no ->get_acl() calls in RCU mode... */ 2683567866bSAl Viro if (acl == ACL_NOT_CACHED) 269e77819e5SLinus Torvalds return -ECHILD; 270206b1d09SAri Savolainen return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK); 271e77819e5SLinus Torvalds } 272e77819e5SLinus Torvalds 2732982baa2SChristoph Hellwig acl = get_acl(inode, ACL_TYPE_ACCESS); 2744e34e719SChristoph Hellwig if (IS_ERR(acl)) 2754e34e719SChristoph Hellwig return PTR_ERR(acl); 276e77819e5SLinus Torvalds if (acl) { 277e77819e5SLinus Torvalds int error = posix_acl_permission(inode, acl, mask); 278e77819e5SLinus Torvalds posix_acl_release(acl); 279e77819e5SLinus Torvalds return error; 280e77819e5SLinus Torvalds } 28184635d68SLinus Torvalds #endif 282e77819e5SLinus Torvalds 283e77819e5SLinus Torvalds return -EAGAIN; 284e77819e5SLinus Torvalds } 285e77819e5SLinus Torvalds 2865909ccaaSLinus Torvalds /* 287948409c7SAndreas Gruenbacher * This does the basic permission checking 2885909ccaaSLinus Torvalds */ 2897e40145eSAl Viro static int acl_permission_check(struct inode *inode, int mask) 2905909ccaaSLinus Torvalds { 29126cf46beSLinus Torvalds unsigned int mode = inode->i_mode; 2925909ccaaSLinus Torvalds 2938e96e3b7SEric W. Biederman if (likely(uid_eq(current_fsuid(), inode->i_uid))) 2945909ccaaSLinus Torvalds mode >>= 6; 2955909ccaaSLinus Torvalds else { 296e77819e5SLinus Torvalds if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { 2977e40145eSAl Viro int error = check_acl(inode, mask); 2985909ccaaSLinus Torvalds if (error != -EAGAIN) 2995909ccaaSLinus Torvalds return error; 3005909ccaaSLinus Torvalds } 3015909ccaaSLinus Torvalds 3025909ccaaSLinus Torvalds if (in_group_p(inode->i_gid)) 3035909ccaaSLinus Torvalds mode >>= 3; 3045909ccaaSLinus Torvalds } 3055909ccaaSLinus Torvalds 3065909ccaaSLinus Torvalds /* 3075909ccaaSLinus Torvalds * If the DACs are ok we don't need any capability check. 3085909ccaaSLinus Torvalds */ 3099c2c7039SAl Viro if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0) 3105909ccaaSLinus Torvalds return 0; 3115909ccaaSLinus Torvalds return -EACCES; 3125909ccaaSLinus Torvalds } 3131da177e4SLinus Torvalds 3141da177e4SLinus Torvalds /** 3151da177e4SLinus Torvalds * generic_permission - check for access rights on a Posix-like filesystem 3161da177e4SLinus Torvalds * @inode: inode to check access rights for 3178fd90c8dSAndreas Gruenbacher * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...) 3181da177e4SLinus Torvalds * 3191da177e4SLinus Torvalds * Used to check for read/write/execute permissions on a file. 3201da177e4SLinus Torvalds * We use "fsuid" for this, letting us set arbitrary permissions 3211da177e4SLinus Torvalds * for filesystem access without changing the "normal" uids which 322b74c79e9SNick Piggin * are used for other things. 323b74c79e9SNick Piggin * 324b74c79e9SNick Piggin * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk 325b74c79e9SNick Piggin * request cannot be satisfied (eg. requires blocking or too much complexity). 326b74c79e9SNick Piggin * It would then be called again in ref-walk mode. 3271da177e4SLinus Torvalds */ 3282830ba7fSAl Viro int generic_permission(struct inode *inode, int mask) 3291da177e4SLinus Torvalds { 3305909ccaaSLinus Torvalds int ret; 3311da177e4SLinus Torvalds 3321da177e4SLinus Torvalds /* 333948409c7SAndreas Gruenbacher * Do the basic permission checks. 3341da177e4SLinus Torvalds */ 3357e40145eSAl Viro ret = acl_permission_check(inode, mask); 3365909ccaaSLinus Torvalds if (ret != -EACCES) 3375909ccaaSLinus Torvalds return ret; 3381da177e4SLinus Torvalds 339d594e7ecSAl Viro if (S_ISDIR(inode->i_mode)) { 340d594e7ecSAl Viro /* DACs are overridable for directories */ 34123adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 342d594e7ecSAl Viro return 0; 343d594e7ecSAl Viro if (!(mask & MAY_WRITE)) 34423adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, 34523adbe12SAndy Lutomirski CAP_DAC_READ_SEARCH)) 346d594e7ecSAl Viro return 0; 347d594e7ecSAl Viro return -EACCES; 348d594e7ecSAl Viro } 3491da177e4SLinus Torvalds /* 3501da177e4SLinus Torvalds * Read/write DACs are always overridable. 351d594e7ecSAl Viro * Executable DACs are overridable when there is 352d594e7ecSAl Viro * at least one exec bit set. 3531da177e4SLinus Torvalds */ 354d594e7ecSAl Viro if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO)) 35523adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE)) 3561da177e4SLinus Torvalds return 0; 3571da177e4SLinus Torvalds 3581da177e4SLinus Torvalds /* 3591da177e4SLinus Torvalds * Searching includes executable on directories, else just read. 3601da177e4SLinus Torvalds */ 3617ea66001SSerge E. Hallyn mask &= MAY_READ | MAY_WRITE | MAY_EXEC; 362d594e7ecSAl Viro if (mask == MAY_READ) 36323adbe12SAndy Lutomirski if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH)) 3641da177e4SLinus Torvalds return 0; 3651da177e4SLinus Torvalds 3661da177e4SLinus Torvalds return -EACCES; 3671da177e4SLinus Torvalds } 3684d359507SAl Viro EXPORT_SYMBOL(generic_permission); 3691da177e4SLinus Torvalds 3703ddcd056SLinus Torvalds /* 3713ddcd056SLinus Torvalds * We _really_ want to just do "generic_permission()" without 3723ddcd056SLinus Torvalds * even looking at the inode->i_op values. So we keep a cache 3733ddcd056SLinus Torvalds * flag in inode->i_opflags, that says "this has not special 3743ddcd056SLinus Torvalds * permission function, use the fast case". 3753ddcd056SLinus Torvalds */ 3763ddcd056SLinus Torvalds static inline int do_inode_permission(struct inode *inode, int mask) 3773ddcd056SLinus Torvalds { 3783ddcd056SLinus Torvalds if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) { 3793ddcd056SLinus Torvalds if (likely(inode->i_op->permission)) 3803ddcd056SLinus Torvalds return inode->i_op->permission(inode, mask); 3813ddcd056SLinus Torvalds 3823ddcd056SLinus Torvalds /* This gets set once for the inode lifetime */ 3833ddcd056SLinus Torvalds spin_lock(&inode->i_lock); 3843ddcd056SLinus Torvalds inode->i_opflags |= IOP_FASTPERM; 3853ddcd056SLinus Torvalds spin_unlock(&inode->i_lock); 3863ddcd056SLinus Torvalds } 3873ddcd056SLinus Torvalds return generic_permission(inode, mask); 3883ddcd056SLinus Torvalds } 3893ddcd056SLinus Torvalds 390cb23beb5SChristoph Hellwig /** 3910bdaea90SDavid Howells * __inode_permission - Check for access rights to a given inode 3920bdaea90SDavid Howells * @inode: Inode to check permission on 3930bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 394cb23beb5SChristoph Hellwig * 3950bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. 396948409c7SAndreas Gruenbacher * 397948409c7SAndreas Gruenbacher * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 3980bdaea90SDavid Howells * 3990bdaea90SDavid Howells * This does not check for a read-only file system. You probably want 4000bdaea90SDavid Howells * inode_permission(). 401cb23beb5SChristoph Hellwig */ 4020bdaea90SDavid Howells int __inode_permission(struct inode *inode, int mask) 4031da177e4SLinus Torvalds { 404e6305c43SAl Viro int retval; 4051da177e4SLinus Torvalds 4063ddcd056SLinus Torvalds if (unlikely(mask & MAY_WRITE)) { 4071da177e4SLinus Torvalds /* 4081da177e4SLinus Torvalds * Nobody gets write access to an immutable file. 4091da177e4SLinus Torvalds */ 4101da177e4SLinus Torvalds if (IS_IMMUTABLE(inode)) 4111da177e4SLinus Torvalds return -EACCES; 4121da177e4SLinus Torvalds } 4131da177e4SLinus Torvalds 4143ddcd056SLinus Torvalds retval = do_inode_permission(inode, mask); 4151da177e4SLinus Torvalds if (retval) 4161da177e4SLinus Torvalds return retval; 4171da177e4SLinus Torvalds 41808ce5f16SSerge E. Hallyn retval = devcgroup_inode_permission(inode, mask); 41908ce5f16SSerge E. Hallyn if (retval) 42008ce5f16SSerge E. Hallyn return retval; 42108ce5f16SSerge E. Hallyn 422d09ca739SEric Paris return security_inode_permission(inode, mask); 4231da177e4SLinus Torvalds } 424bd5d0856SMiklos Szeredi EXPORT_SYMBOL(__inode_permission); 4251da177e4SLinus Torvalds 426f4d6ff89SAl Viro /** 4270bdaea90SDavid Howells * sb_permission - Check superblock-level permissions 4280bdaea90SDavid Howells * @sb: Superblock of inode to check permission on 42955852635SRandy Dunlap * @inode: Inode to check permission on 4300bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4310bdaea90SDavid Howells * 4320bdaea90SDavid Howells * Separate out file-system wide checks from inode-specific permission checks. 4330bdaea90SDavid Howells */ 4340bdaea90SDavid Howells static int sb_permission(struct super_block *sb, struct inode *inode, int mask) 4350bdaea90SDavid Howells { 4360bdaea90SDavid Howells if (unlikely(mask & MAY_WRITE)) { 4370bdaea90SDavid Howells umode_t mode = inode->i_mode; 4380bdaea90SDavid Howells 4390bdaea90SDavid Howells /* Nobody gets write access to a read-only fs. */ 4400bdaea90SDavid Howells if ((sb->s_flags & MS_RDONLY) && 4410bdaea90SDavid Howells (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) 4420bdaea90SDavid Howells return -EROFS; 4430bdaea90SDavid Howells } 4440bdaea90SDavid Howells return 0; 4450bdaea90SDavid Howells } 4460bdaea90SDavid Howells 4470bdaea90SDavid Howells /** 4480bdaea90SDavid Howells * inode_permission - Check for access rights to a given inode 4490bdaea90SDavid Howells * @inode: Inode to check permission on 4500bdaea90SDavid Howells * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) 4510bdaea90SDavid Howells * 4520bdaea90SDavid Howells * Check for read/write/execute permissions on an inode. We use fs[ug]id for 4530bdaea90SDavid Howells * this, letting us set arbitrary permissions for filesystem access without 4540bdaea90SDavid Howells * changing the "normal" UIDs which are used for other things. 4550bdaea90SDavid Howells * 4560bdaea90SDavid Howells * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask. 4570bdaea90SDavid Howells */ 4580bdaea90SDavid Howells int inode_permission(struct inode *inode, int mask) 4590bdaea90SDavid Howells { 4600bdaea90SDavid Howells int retval; 4610bdaea90SDavid Howells 4620bdaea90SDavid Howells retval = sb_permission(inode->i_sb, inode, mask); 4630bdaea90SDavid Howells if (retval) 4640bdaea90SDavid Howells return retval; 4650bdaea90SDavid Howells return __inode_permission(inode, mask); 4660bdaea90SDavid Howells } 4674d359507SAl Viro EXPORT_SYMBOL(inode_permission); 4680bdaea90SDavid Howells 4690bdaea90SDavid Howells /** 4705dd784d0SJan Blunck * path_get - get a reference to a path 4715dd784d0SJan Blunck * @path: path to get the reference to 4725dd784d0SJan Blunck * 4735dd784d0SJan Blunck * Given a path increment the reference count to the dentry and the vfsmount. 4745dd784d0SJan Blunck */ 475dcf787f3SAl Viro void path_get(const struct path *path) 4765dd784d0SJan Blunck { 4775dd784d0SJan Blunck mntget(path->mnt); 4785dd784d0SJan Blunck dget(path->dentry); 4795dd784d0SJan Blunck } 4805dd784d0SJan Blunck EXPORT_SYMBOL(path_get); 4815dd784d0SJan Blunck 4825dd784d0SJan Blunck /** 4831d957f9bSJan Blunck * path_put - put a reference to a path 4841d957f9bSJan Blunck * @path: path to put the reference to 4851d957f9bSJan Blunck * 4861d957f9bSJan Blunck * Given a path decrement the reference count to the dentry and the vfsmount. 4871d957f9bSJan Blunck */ 488dcf787f3SAl Viro void path_put(const struct path *path) 4891da177e4SLinus Torvalds { 4901d957f9bSJan Blunck dput(path->dentry); 4911d957f9bSJan Blunck mntput(path->mnt); 4921da177e4SLinus Torvalds } 4931d957f9bSJan Blunck EXPORT_SYMBOL(path_put); 4941da177e4SLinus Torvalds 4951f55a6ecSAl Viro struct nameidata { 4961f55a6ecSAl Viro struct path path; 497caa85634SAl Viro union { 4981f55a6ecSAl Viro struct qstr last; 499caa85634SAl Viro struct path link; 500caa85634SAl Viro }; 5011f55a6ecSAl Viro struct path root; 5021f55a6ecSAl Viro struct inode *inode; /* path.dentry.d_inode */ 5031f55a6ecSAl Viro unsigned int flags; 5041f55a6ecSAl Viro unsigned seq, m_seq; 5051f55a6ecSAl Viro int last_type; 5061f55a6ecSAl Viro unsigned depth; 5075e53084dSAl Viro struct file *base; 5081f55a6ecSAl Viro }; 5091f55a6ecSAl Viro 51019660af7SAl Viro /* 51131e6b01fSNick Piggin * Path walking has 2 modes, rcu-walk and ref-walk (see 51219660af7SAl Viro * Documentation/filesystems/path-lookup.txt). In situations when we can't 51319660af7SAl Viro * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab 51419660af7SAl Viro * normal reference counts on dentries and vfsmounts to transition to rcu-walk 51519660af7SAl Viro * mode. Refcounts are grabbed at the last known good point before rcu-walk 51619660af7SAl Viro * got stuck, so ref-walk may continue from there. If this is not successful 51719660af7SAl Viro * (eg. a seqcount has changed), then failure is returned and it's up to caller 51819660af7SAl Viro * to restart the path walk from the beginning in ref-walk mode. 51931e6b01fSNick Piggin */ 52031e6b01fSNick Piggin 52131e6b01fSNick Piggin /** 52219660af7SAl Viro * unlazy_walk - try to switch to ref-walk mode. 52319660af7SAl Viro * @nd: nameidata pathwalk data 52419660af7SAl Viro * @dentry: child of nd->path.dentry or NULL 52539191628SRandy Dunlap * Returns: 0 on success, -ECHILD on failure 52631e6b01fSNick Piggin * 52719660af7SAl Viro * unlazy_walk attempts to legitimize the current nd->path, nd->root and dentry 52819660af7SAl Viro * for ref-walk mode. @dentry must be a path found by a do_lookup call on 52919660af7SAl Viro * @nd or NULL. Must be called from rcu-walk context. 53031e6b01fSNick Piggin */ 53119660af7SAl Viro static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) 53231e6b01fSNick Piggin { 53331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 53431e6b01fSNick Piggin struct dentry *parent = nd->path.dentry; 53531e6b01fSNick Piggin 53631e6b01fSNick Piggin BUG_ON(!(nd->flags & LOOKUP_RCU)); 537e5c832d5SLinus Torvalds 538e5c832d5SLinus Torvalds /* 53948a066e7SAl Viro * After legitimizing the bastards, terminate_walk() 54048a066e7SAl Viro * will do the right thing for non-RCU mode, and all our 54148a066e7SAl Viro * subsequent exit cases should rcu_read_unlock() 54248a066e7SAl Viro * before returning. Do vfsmount first; if dentry 54348a066e7SAl Viro * can't be legitimized, just set nd->path.dentry to NULL 54448a066e7SAl Viro * and rely on dput(NULL) being a no-op. 545e5c832d5SLinus Torvalds */ 54648a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) 547e5c832d5SLinus Torvalds return -ECHILD; 548e5c832d5SLinus Torvalds nd->flags &= ~LOOKUP_RCU; 54915570086SLinus Torvalds 55048a066e7SAl Viro if (!lockref_get_not_dead(&parent->d_lockref)) { 55148a066e7SAl Viro nd->path.dentry = NULL; 552d870b4a1SAl Viro goto out; 55348a066e7SAl Viro } 55448a066e7SAl Viro 55515570086SLinus Torvalds /* 55615570086SLinus Torvalds * For a negative lookup, the lookup sequence point is the parents 55715570086SLinus Torvalds * sequence point, and it only needs to revalidate the parent dentry. 55815570086SLinus Torvalds * 55915570086SLinus Torvalds * For a positive lookup, we need to move both the parent and the 56015570086SLinus Torvalds * dentry from the RCU domain to be properly refcounted. And the 56115570086SLinus Torvalds * sequence number in the dentry validates *both* dentry counters, 56215570086SLinus Torvalds * since we checked the sequence number of the parent after we got 56315570086SLinus Torvalds * the child sequence number. So we know the parent must still 56415570086SLinus Torvalds * be valid if the child sequence number is still valid. 56515570086SLinus Torvalds */ 56619660af7SAl Viro if (!dentry) { 567e5c832d5SLinus Torvalds if (read_seqcount_retry(&parent->d_seq, nd->seq)) 568e5c832d5SLinus Torvalds goto out; 56919660af7SAl Viro BUG_ON(nd->inode != parent->d_inode); 57019660af7SAl Viro } else { 571e5c832d5SLinus Torvalds if (!lockref_get_not_dead(&dentry->d_lockref)) 572e5c832d5SLinus Torvalds goto out; 573e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) 574e5c832d5SLinus Torvalds goto drop_dentry; 57519660af7SAl Viro } 576e5c832d5SLinus Torvalds 577e5c832d5SLinus Torvalds /* 578e5c832d5SLinus Torvalds * Sequence counts matched. Now make sure that the root is 579e5c832d5SLinus Torvalds * still valid and get it if required. 580e5c832d5SLinus Torvalds */ 581e5c832d5SLinus Torvalds if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 582e5c832d5SLinus Torvalds spin_lock(&fs->lock); 583e5c832d5SLinus Torvalds if (nd->root.mnt != fs->root.mnt || nd->root.dentry != fs->root.dentry) 584e5c832d5SLinus Torvalds goto unlock_and_drop_dentry; 58531e6b01fSNick Piggin path_get(&nd->root); 58631e6b01fSNick Piggin spin_unlock(&fs->lock); 58731e6b01fSNick Piggin } 58831e6b01fSNick Piggin 5898b61e74fSAl Viro rcu_read_unlock(); 59031e6b01fSNick Piggin return 0; 59119660af7SAl Viro 592e5c832d5SLinus Torvalds unlock_and_drop_dentry: 59331e6b01fSNick Piggin spin_unlock(&fs->lock); 594e5c832d5SLinus Torvalds drop_dentry: 5958b61e74fSAl Viro rcu_read_unlock(); 596e5c832d5SLinus Torvalds dput(dentry); 597d0d27277SLinus Torvalds goto drop_root_mnt; 598e5c832d5SLinus Torvalds out: 5998b61e74fSAl Viro rcu_read_unlock(); 600d0d27277SLinus Torvalds drop_root_mnt: 601d0d27277SLinus Torvalds if (!(nd->flags & LOOKUP_ROOT)) 602d0d27277SLinus Torvalds nd->root.mnt = NULL; 60331e6b01fSNick Piggin return -ECHILD; 60431e6b01fSNick Piggin } 60531e6b01fSNick Piggin 6064ce16ef3SAl Viro static inline int d_revalidate(struct dentry *dentry, unsigned int flags) 60734286d66SNick Piggin { 6084ce16ef3SAl Viro return dentry->d_op->d_revalidate(dentry, flags); 60934286d66SNick Piggin } 61034286d66SNick Piggin 6119f1fafeeSAl Viro /** 6129f1fafeeSAl Viro * complete_walk - successful completion of path walk 6139f1fafeeSAl Viro * @nd: pointer nameidata 61439159de2SJeff Layton * 6159f1fafeeSAl Viro * If we had been in RCU mode, drop out of it and legitimize nd->path. 6169f1fafeeSAl Viro * Revalidate the final result, unless we'd already done that during 6179f1fafeeSAl Viro * the path walk or the filesystem doesn't ask for it. Return 0 on 6189f1fafeeSAl Viro * success, -error on failure. In case of failure caller does not 6199f1fafeeSAl Viro * need to drop nd->path. 62039159de2SJeff Layton */ 6219f1fafeeSAl Viro static int complete_walk(struct nameidata *nd) 62239159de2SJeff Layton { 62316c2cd71SAl Viro struct dentry *dentry = nd->path.dentry; 62439159de2SJeff Layton int status; 62539159de2SJeff Layton 6269f1fafeeSAl Viro if (nd->flags & LOOKUP_RCU) { 6279f1fafeeSAl Viro nd->flags &= ~LOOKUP_RCU; 6289f1fafeeSAl Viro if (!(nd->flags & LOOKUP_ROOT)) 6299f1fafeeSAl Viro nd->root.mnt = NULL; 63015570086SLinus Torvalds 63148a066e7SAl Viro if (!legitimize_mnt(nd->path.mnt, nd->m_seq)) { 6328b61e74fSAl Viro rcu_read_unlock(); 63348a066e7SAl Viro return -ECHILD; 63448a066e7SAl Viro } 635e5c832d5SLinus Torvalds if (unlikely(!lockref_get_not_dead(&dentry->d_lockref))) { 6368b61e74fSAl Viro rcu_read_unlock(); 63748a066e7SAl Viro mntput(nd->path.mnt); 6389f1fafeeSAl Viro return -ECHILD; 6399f1fafeeSAl Viro } 640e5c832d5SLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, nd->seq)) { 6418b61e74fSAl Viro rcu_read_unlock(); 642e5c832d5SLinus Torvalds dput(dentry); 64348a066e7SAl Viro mntput(nd->path.mnt); 644e5c832d5SLinus Torvalds return -ECHILD; 645e5c832d5SLinus Torvalds } 6468b61e74fSAl Viro rcu_read_unlock(); 6479f1fafeeSAl Viro } 6489f1fafeeSAl Viro 64916c2cd71SAl Viro if (likely(!(nd->flags & LOOKUP_JUMPED))) 65039159de2SJeff Layton return 0; 65139159de2SJeff Layton 652ecf3d1f1SJeff Layton if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE))) 65316c2cd71SAl Viro return 0; 65416c2cd71SAl Viro 655ecf3d1f1SJeff Layton status = dentry->d_op->d_weak_revalidate(dentry, nd->flags); 65639159de2SJeff Layton if (status > 0) 65739159de2SJeff Layton return 0; 65839159de2SJeff Layton 65916c2cd71SAl Viro if (!status) 66039159de2SJeff Layton status = -ESTALE; 66116c2cd71SAl Viro 6629f1fafeeSAl Viro path_put(&nd->path); 66339159de2SJeff Layton return status; 66439159de2SJeff Layton } 66539159de2SJeff Layton 6662a737871SAl Viro static __always_inline void set_root(struct nameidata *nd) 6672a737871SAl Viro { 668f7ad3c6bSMiklos Szeredi get_fs_root(current->fs, &nd->root); 6692a737871SAl Viro } 6702a737871SAl Viro 6717bd88377SAl Viro static __always_inline unsigned set_root_rcu(struct nameidata *nd) 67231e6b01fSNick Piggin { 67331e6b01fSNick Piggin struct fs_struct *fs = current->fs; 6747bd88377SAl Viro unsigned seq, res; 675c28cc364SNick Piggin 676c28cc364SNick Piggin do { 677c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 67831e6b01fSNick Piggin nd->root = fs->root; 6797bd88377SAl Viro res = __read_seqcount_begin(&nd->root.dentry->d_seq); 680c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 6817bd88377SAl Viro return res; 68231e6b01fSNick Piggin } 68331e6b01fSNick Piggin 6841d957f9bSJan Blunck static void path_put_conditional(struct path *path, struct nameidata *nd) 685051d3812SIan Kent { 686051d3812SIan Kent dput(path->dentry); 6874ac91378SJan Blunck if (path->mnt != nd->path.mnt) 688051d3812SIan Kent mntput(path->mnt); 689051d3812SIan Kent } 690051d3812SIan Kent 6917b9337aaSNick Piggin static inline void path_to_nameidata(const struct path *path, 6927b9337aaSNick Piggin struct nameidata *nd) 693051d3812SIan Kent { 69431e6b01fSNick Piggin if (!(nd->flags & LOOKUP_RCU)) { 6954ac91378SJan Blunck dput(nd->path.dentry); 69631e6b01fSNick Piggin if (nd->path.mnt != path->mnt) 6974ac91378SJan Blunck mntput(nd->path.mnt); 6989a229683SHuang Shijie } 69931e6b01fSNick Piggin nd->path.mnt = path->mnt; 7004ac91378SJan Blunck nd->path.dentry = path->dentry; 701051d3812SIan Kent } 702051d3812SIan Kent 703b5fb63c1SChristoph Hellwig /* 704b5fb63c1SChristoph Hellwig * Helper to directly jump to a known parsed path from ->follow_link, 705b5fb63c1SChristoph Hellwig * caller must have taken a reference to path beforehand. 706b5fb63c1SChristoph Hellwig */ 707b5fb63c1SChristoph Hellwig void nd_jump_link(struct nameidata *nd, struct path *path) 708b5fb63c1SChristoph Hellwig { 709b5fb63c1SChristoph Hellwig path_put(&nd->path); 710b5fb63c1SChristoph Hellwig 711b5fb63c1SChristoph Hellwig nd->path = *path; 712b5fb63c1SChristoph Hellwig nd->inode = nd->path.dentry->d_inode; 713b5fb63c1SChristoph Hellwig nd->flags |= LOOKUP_JUMPED; 714b5fb63c1SChristoph Hellwig } 715b5fb63c1SChristoph Hellwig 716574197e0SAl Viro static inline void put_link(struct nameidata *nd, struct path *link, void *cookie) 717574197e0SAl Viro { 718574197e0SAl Viro struct inode *inode = link->dentry->d_inode; 719680baacbSAl Viro if (cookie && inode->i_op->put_link) 720680baacbSAl Viro inode->i_op->put_link(link->dentry, cookie); 721574197e0SAl Viro path_put(link); 722574197e0SAl Viro } 723574197e0SAl Viro 724561ec64aSLinus Torvalds int sysctl_protected_symlinks __read_mostly = 0; 725561ec64aSLinus Torvalds int sysctl_protected_hardlinks __read_mostly = 0; 726800179c9SKees Cook 727800179c9SKees Cook /** 728800179c9SKees Cook * may_follow_link - Check symlink following for unsafe situations 729800179c9SKees Cook * @link: The path of the symlink 73055852635SRandy Dunlap * @nd: nameidata pathwalk data 731800179c9SKees Cook * 732800179c9SKees Cook * In the case of the sysctl_protected_symlinks sysctl being enabled, 733800179c9SKees Cook * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is 734800179c9SKees Cook * in a sticky world-writable directory. This is to protect privileged 735800179c9SKees Cook * processes from failing races against path names that may change out 736800179c9SKees Cook * from under them by way of other users creating malicious symlinks. 737800179c9SKees Cook * It will permit symlinks to be followed only when outside a sticky 738800179c9SKees Cook * world-writable directory, or when the uid of the symlink and follower 739800179c9SKees Cook * match, or when the directory owner matches the symlink's owner. 740800179c9SKees Cook * 741800179c9SKees Cook * Returns 0 if following the symlink is allowed, -ve on error. 742800179c9SKees Cook */ 743800179c9SKees Cook static inline int may_follow_link(struct path *link, struct nameidata *nd) 744800179c9SKees Cook { 745800179c9SKees Cook const struct inode *inode; 746800179c9SKees Cook const struct inode *parent; 747800179c9SKees Cook 748800179c9SKees Cook if (!sysctl_protected_symlinks) 749800179c9SKees Cook return 0; 750800179c9SKees Cook 751800179c9SKees Cook /* Allowed if owner and follower match. */ 752800179c9SKees Cook inode = link->dentry->d_inode; 75381abe27bSEric W. Biederman if (uid_eq(current_cred()->fsuid, inode->i_uid)) 754800179c9SKees Cook return 0; 755800179c9SKees Cook 756800179c9SKees Cook /* Allowed if parent directory not sticky and world-writable. */ 757800179c9SKees Cook parent = nd->path.dentry->d_inode; 758800179c9SKees Cook if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH)) 759800179c9SKees Cook return 0; 760800179c9SKees Cook 761800179c9SKees Cook /* Allowed if parent directory and link owner match. */ 76281abe27bSEric W. Biederman if (uid_eq(parent->i_uid, inode->i_uid)) 763800179c9SKees Cook return 0; 764800179c9SKees Cook 765ffd8d101SSasha Levin audit_log_link_denied("follow_link", link); 766800179c9SKees Cook path_put_conditional(link, nd); 767800179c9SKees Cook path_put(&nd->path); 768800179c9SKees Cook return -EACCES; 769800179c9SKees Cook } 770800179c9SKees Cook 771800179c9SKees Cook /** 772800179c9SKees Cook * safe_hardlink_source - Check for safe hardlink conditions 773800179c9SKees Cook * @inode: the source inode to hardlink from 774800179c9SKees Cook * 775800179c9SKees Cook * Return false if at least one of the following conditions: 776800179c9SKees Cook * - inode is not a regular file 777800179c9SKees Cook * - inode is setuid 778800179c9SKees Cook * - inode is setgid and group-exec 779800179c9SKees Cook * - access failure for read and write 780800179c9SKees Cook * 781800179c9SKees Cook * Otherwise returns true. 782800179c9SKees Cook */ 783800179c9SKees Cook static bool safe_hardlink_source(struct inode *inode) 784800179c9SKees Cook { 785800179c9SKees Cook umode_t mode = inode->i_mode; 786800179c9SKees Cook 787800179c9SKees Cook /* Special files should not get pinned to the filesystem. */ 788800179c9SKees Cook if (!S_ISREG(mode)) 789800179c9SKees Cook return false; 790800179c9SKees Cook 791800179c9SKees Cook /* Setuid files should not get pinned to the filesystem. */ 792800179c9SKees Cook if (mode & S_ISUID) 793800179c9SKees Cook return false; 794800179c9SKees Cook 795800179c9SKees Cook /* Executable setgid files should not get pinned to the filesystem. */ 796800179c9SKees Cook if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 797800179c9SKees Cook return false; 798800179c9SKees Cook 799800179c9SKees Cook /* Hardlinking to unreadable or unwritable sources is dangerous. */ 800800179c9SKees Cook if (inode_permission(inode, MAY_READ | MAY_WRITE)) 801800179c9SKees Cook return false; 802800179c9SKees Cook 803800179c9SKees Cook return true; 804800179c9SKees Cook } 805800179c9SKees Cook 806800179c9SKees Cook /** 807800179c9SKees Cook * may_linkat - Check permissions for creating a hardlink 808800179c9SKees Cook * @link: the source to hardlink from 809800179c9SKees Cook * 810800179c9SKees Cook * Block hardlink when all of: 811800179c9SKees Cook * - sysctl_protected_hardlinks enabled 812800179c9SKees Cook * - fsuid does not match inode 813800179c9SKees Cook * - hardlink source is unsafe (see safe_hardlink_source() above) 814800179c9SKees Cook * - not CAP_FOWNER 815800179c9SKees Cook * 816800179c9SKees Cook * Returns 0 if successful, -ve on error. 817800179c9SKees Cook */ 818800179c9SKees Cook static int may_linkat(struct path *link) 819800179c9SKees Cook { 820800179c9SKees Cook const struct cred *cred; 821800179c9SKees Cook struct inode *inode; 822800179c9SKees Cook 823800179c9SKees Cook if (!sysctl_protected_hardlinks) 824800179c9SKees Cook return 0; 825800179c9SKees Cook 826800179c9SKees Cook cred = current_cred(); 827800179c9SKees Cook inode = link->dentry->d_inode; 828800179c9SKees Cook 829800179c9SKees Cook /* Source inode owner (or CAP_FOWNER) can hardlink all they like, 830800179c9SKees Cook * otherwise, it must be a safe source. 831800179c9SKees Cook */ 83281abe27bSEric W. Biederman if (uid_eq(cred->fsuid, inode->i_uid) || safe_hardlink_source(inode) || 833800179c9SKees Cook capable(CAP_FOWNER)) 834800179c9SKees Cook return 0; 835800179c9SKees Cook 836a51d9eaaSKees Cook audit_log_link_denied("linkat", link); 837800179c9SKees Cook return -EPERM; 838800179c9SKees Cook } 839800179c9SKees Cook 8400a959df5SAl Viro static __always_inline const char * 8410a959df5SAl Viro get_link(struct path *link, struct nameidata *nd, void **p) 8421da177e4SLinus Torvalds { 8437b9337aaSNick Piggin struct dentry *dentry = link->dentry; 8440a959df5SAl Viro struct inode *inode = dentry->d_inode; 8456d7b5aaeSAl Viro int error; 8460a959df5SAl Viro const char *res; 8471da177e4SLinus Torvalds 848844a3917SAl Viro BUG_ON(nd->flags & LOOKUP_RCU); 849844a3917SAl Viro 8500e794589SAl Viro if (link->mnt == nd->path.mnt) 8510e794589SAl Viro mntget(link->mnt); 8520e794589SAl Viro 8530a959df5SAl Viro res = ERR_PTR(-ELOOP); 8546d7b5aaeSAl Viro if (unlikely(current->total_link_count >= 40)) 8550a959df5SAl Viro goto out; 8566d7b5aaeSAl Viro 857574197e0SAl Viro cond_resched(); 858574197e0SAl Viro current->total_link_count++; 859574197e0SAl Viro 86068ac1234SAl Viro touch_atime(link); 861cd4e91d3SAl Viro 86237882db0SNeilBrown error = security_inode_follow_link(dentry); 8630a959df5SAl Viro res = ERR_PTR(error); 8646d7b5aaeSAl Viro if (error) 8650a959df5SAl Viro goto out; 86636f3b4f6SAl Viro 86786acdca1SAl Viro nd->last_type = LAST_BIND; 868680baacbSAl Viro *p = NULL; 869d4dee48bSAl Viro res = inode->i_link; 870d4dee48bSAl Viro if (!res) { 8710a959df5SAl Viro res = inode->i_op->follow_link(dentry, p, nd); 8720a959df5SAl Viro if (IS_ERR(res)) { 8730a959df5SAl Viro out: 8740a959df5SAl Viro path_put(&nd->path); 8750a959df5SAl Viro path_put(link); 8760a959df5SAl Viro } 877d4dee48bSAl Viro } 8780a959df5SAl Viro return res; 8790a959df5SAl Viro } 8806d7b5aaeSAl Viro 88131e6b01fSNick Piggin static int follow_up_rcu(struct path *path) 88231e6b01fSNick Piggin { 8830714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 8840714a533SAl Viro struct mount *parent; 88531e6b01fSNick Piggin struct dentry *mountpoint; 88631e6b01fSNick Piggin 8870714a533SAl Viro parent = mnt->mnt_parent; 8880714a533SAl Viro if (&parent->mnt == path->mnt) 88931e6b01fSNick Piggin return 0; 890a73324daSAl Viro mountpoint = mnt->mnt_mountpoint; 89131e6b01fSNick Piggin path->dentry = mountpoint; 8920714a533SAl Viro path->mnt = &parent->mnt; 89331e6b01fSNick Piggin return 1; 89431e6b01fSNick Piggin } 89531e6b01fSNick Piggin 896f015f126SDavid Howells /* 897f015f126SDavid Howells * follow_up - Find the mountpoint of path's vfsmount 898f015f126SDavid Howells * 899f015f126SDavid Howells * Given a path, find the mountpoint of its source file system. 900f015f126SDavid Howells * Replace @path with the path of the mountpoint in the parent mount. 901f015f126SDavid Howells * Up is towards /. 902f015f126SDavid Howells * 903f015f126SDavid Howells * Return 1 if we went up a level and 0 if we were already at the 904f015f126SDavid Howells * root. 905f015f126SDavid Howells */ 906bab77ebfSAl Viro int follow_up(struct path *path) 9071da177e4SLinus Torvalds { 9080714a533SAl Viro struct mount *mnt = real_mount(path->mnt); 9090714a533SAl Viro struct mount *parent; 9101da177e4SLinus Torvalds struct dentry *mountpoint; 91199b7db7bSNick Piggin 91248a066e7SAl Viro read_seqlock_excl(&mount_lock); 9130714a533SAl Viro parent = mnt->mnt_parent; 9143c0a6163SAl Viro if (parent == mnt) { 91548a066e7SAl Viro read_sequnlock_excl(&mount_lock); 9161da177e4SLinus Torvalds return 0; 9171da177e4SLinus Torvalds } 9180714a533SAl Viro mntget(&parent->mnt); 919a73324daSAl Viro mountpoint = dget(mnt->mnt_mountpoint); 92048a066e7SAl Viro read_sequnlock_excl(&mount_lock); 921bab77ebfSAl Viro dput(path->dentry); 922bab77ebfSAl Viro path->dentry = mountpoint; 923bab77ebfSAl Viro mntput(path->mnt); 9240714a533SAl Viro path->mnt = &parent->mnt; 9251da177e4SLinus Torvalds return 1; 9261da177e4SLinus Torvalds } 9274d359507SAl Viro EXPORT_SYMBOL(follow_up); 9281da177e4SLinus Torvalds 929b5c84bf6SNick Piggin /* 9309875cf80SDavid Howells * Perform an automount 9319875cf80SDavid Howells * - return -EISDIR to tell follow_managed() to stop and return the path we 9329875cf80SDavid Howells * were called with. 9331da177e4SLinus Torvalds */ 9349875cf80SDavid Howells static int follow_automount(struct path *path, unsigned flags, 9359875cf80SDavid Howells bool *need_mntput) 93631e6b01fSNick Piggin { 9379875cf80SDavid Howells struct vfsmount *mnt; 938ea5b778aSDavid Howells int err; 9399875cf80SDavid Howells 9409875cf80SDavid Howells if (!path->dentry->d_op || !path->dentry->d_op->d_automount) 9419875cf80SDavid Howells return -EREMOTE; 9429875cf80SDavid Howells 9430ec26fd0SMiklos Szeredi /* We don't want to mount if someone's just doing a stat - 9440ec26fd0SMiklos Szeredi * unless they're stat'ing a directory and appended a '/' to 9450ec26fd0SMiklos Szeredi * the name. 9460ec26fd0SMiklos Szeredi * 9470ec26fd0SMiklos Szeredi * We do, however, want to mount if someone wants to open or 9485a30d8a2SDavid Howells * create a file of any type under the mountpoint, wants to 9490ec26fd0SMiklos Szeredi * traverse through the mountpoint or wants to open the 9500ec26fd0SMiklos Szeredi * mounted directory. Also, autofs may mark negative dentries 9510ec26fd0SMiklos Szeredi * as being automount points. These will need the attentions 9520ec26fd0SMiklos Szeredi * of the daemon to instantiate them before they can be used. 9535a30d8a2SDavid Howells */ 9545a30d8a2SDavid Howells if (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY | 955d94c177bSLinus Torvalds LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) && 9565a30d8a2SDavid Howells path->dentry->d_inode) 9579875cf80SDavid Howells return -EISDIR; 9580ec26fd0SMiklos Szeredi 9599875cf80SDavid Howells current->total_link_count++; 9609875cf80SDavid Howells if (current->total_link_count >= 40) 9619875cf80SDavid Howells return -ELOOP; 9629875cf80SDavid Howells 9639875cf80SDavid Howells mnt = path->dentry->d_op->d_automount(path); 9649875cf80SDavid Howells if (IS_ERR(mnt)) { 9659875cf80SDavid Howells /* 9669875cf80SDavid Howells * The filesystem is allowed to return -EISDIR here to indicate 9679875cf80SDavid Howells * it doesn't want to automount. For instance, autofs would do 9689875cf80SDavid Howells * this so that its userspace daemon can mount on this dentry. 9699875cf80SDavid Howells * 9709875cf80SDavid Howells * However, we can only permit this if it's a terminal point in 9719875cf80SDavid Howells * the path being looked up; if it wasn't then the remainder of 9729875cf80SDavid Howells * the path is inaccessible and we should say so. 9739875cf80SDavid Howells */ 97449084c3bSAl Viro if (PTR_ERR(mnt) == -EISDIR && (flags & LOOKUP_PARENT)) 9759875cf80SDavid Howells return -EREMOTE; 9769875cf80SDavid Howells return PTR_ERR(mnt); 97731e6b01fSNick Piggin } 978ea5b778aSDavid Howells 9799875cf80SDavid Howells if (!mnt) /* mount collision */ 9809875cf80SDavid Howells return 0; 9819875cf80SDavid Howells 9828aef1884SAl Viro if (!*need_mntput) { 9838aef1884SAl Viro /* lock_mount() may release path->mnt on error */ 9848aef1884SAl Viro mntget(path->mnt); 9858aef1884SAl Viro *need_mntput = true; 9868aef1884SAl Viro } 98719a167afSAl Viro err = finish_automount(mnt, path); 988ea5b778aSDavid Howells 989ea5b778aSDavid Howells switch (err) { 990ea5b778aSDavid Howells case -EBUSY: 991ea5b778aSDavid Howells /* Someone else made a mount here whilst we were busy */ 99219a167afSAl Viro return 0; 993ea5b778aSDavid Howells case 0: 9948aef1884SAl Viro path_put(path); 9959875cf80SDavid Howells path->mnt = mnt; 9969875cf80SDavid Howells path->dentry = dget(mnt->mnt_root); 9979875cf80SDavid Howells return 0; 99819a167afSAl Viro default: 99919a167afSAl Viro return err; 10009875cf80SDavid Howells } 100119a167afSAl Viro 1002ea5b778aSDavid Howells } 10039875cf80SDavid Howells 10049875cf80SDavid Howells /* 10059875cf80SDavid Howells * Handle a dentry that is managed in some way. 1006cc53ce53SDavid Howells * - Flagged for transit management (autofs) 10079875cf80SDavid Howells * - Flagged as mountpoint 10089875cf80SDavid Howells * - Flagged as automount point 10099875cf80SDavid Howells * 10109875cf80SDavid Howells * This may only be called in refwalk mode. 10119875cf80SDavid Howells * 10129875cf80SDavid Howells * Serialization is taken care of in namespace.c 10139875cf80SDavid Howells */ 10149875cf80SDavid Howells static int follow_managed(struct path *path, unsigned flags) 10159875cf80SDavid Howells { 10168aef1884SAl Viro struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ 10179875cf80SDavid Howells unsigned managed; 10189875cf80SDavid Howells bool need_mntput = false; 10198aef1884SAl Viro int ret = 0; 10209875cf80SDavid Howells 10219875cf80SDavid Howells /* Given that we're not holding a lock here, we retain the value in a 10229875cf80SDavid Howells * local variable for each dentry as we look at it so that we don't see 10239875cf80SDavid Howells * the components of that value change under us */ 10249875cf80SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 10259875cf80SDavid Howells managed &= DCACHE_MANAGED_DENTRY, 10269875cf80SDavid Howells unlikely(managed != 0)) { 1027cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1028cc53ce53SDavid Howells * being held. */ 1029cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1030cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1031cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 10321aed3e42SAl Viro ret = path->dentry->d_op->d_manage(path->dentry, false); 1033cc53ce53SDavid Howells if (ret < 0) 10348aef1884SAl Viro break; 1035cc53ce53SDavid Howells } 1036cc53ce53SDavid Howells 10379875cf80SDavid Howells /* Transit to a mounted filesystem. */ 10389875cf80SDavid Howells if (managed & DCACHE_MOUNTED) { 10399875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 10409875cf80SDavid Howells if (mounted) { 10419875cf80SDavid Howells dput(path->dentry); 10429875cf80SDavid Howells if (need_mntput) 1043463ffb2eSAl Viro mntput(path->mnt); 1044463ffb2eSAl Viro path->mnt = mounted; 1045463ffb2eSAl Viro path->dentry = dget(mounted->mnt_root); 10469875cf80SDavid Howells need_mntput = true; 10479875cf80SDavid Howells continue; 1048463ffb2eSAl Viro } 1049463ffb2eSAl Viro 10509875cf80SDavid Howells /* Something is mounted on this dentry in another 10519875cf80SDavid Howells * namespace and/or whatever was mounted there in this 105248a066e7SAl Viro * namespace got unmounted before lookup_mnt() could 105348a066e7SAl Viro * get it */ 10541da177e4SLinus Torvalds } 10559875cf80SDavid Howells 10569875cf80SDavid Howells /* Handle an automount point */ 10579875cf80SDavid Howells if (managed & DCACHE_NEED_AUTOMOUNT) { 10589875cf80SDavid Howells ret = follow_automount(path, flags, &need_mntput); 10599875cf80SDavid Howells if (ret < 0) 10608aef1884SAl Viro break; 10619875cf80SDavid Howells continue; 10629875cf80SDavid Howells } 10639875cf80SDavid Howells 10649875cf80SDavid Howells /* We didn't change the current path point */ 10659875cf80SDavid Howells break; 10669875cf80SDavid Howells } 10678aef1884SAl Viro 10688aef1884SAl Viro if (need_mntput && path->mnt == mnt) 10698aef1884SAl Viro mntput(path->mnt); 10708aef1884SAl Viro if (ret == -EISDIR) 10718aef1884SAl Viro ret = 0; 1072a3fbbde7SAl Viro return ret < 0 ? ret : need_mntput; 10731da177e4SLinus Torvalds } 10741da177e4SLinus Torvalds 1075cc53ce53SDavid Howells int follow_down_one(struct path *path) 10761da177e4SLinus Torvalds { 10771da177e4SLinus Torvalds struct vfsmount *mounted; 10781da177e4SLinus Torvalds 10791c755af4SAl Viro mounted = lookup_mnt(path); 10801da177e4SLinus Torvalds if (mounted) { 10819393bd07SAl Viro dput(path->dentry); 10829393bd07SAl Viro mntput(path->mnt); 10839393bd07SAl Viro path->mnt = mounted; 10849393bd07SAl Viro path->dentry = dget(mounted->mnt_root); 10851da177e4SLinus Torvalds return 1; 10861da177e4SLinus Torvalds } 10871da177e4SLinus Torvalds return 0; 10881da177e4SLinus Torvalds } 10894d359507SAl Viro EXPORT_SYMBOL(follow_down_one); 10901da177e4SLinus Torvalds 1091b8faf035SNeilBrown static inline int managed_dentry_rcu(struct dentry *dentry) 109262a7375eSIan Kent { 1093b8faf035SNeilBrown return (dentry->d_flags & DCACHE_MANAGE_TRANSIT) ? 1094b8faf035SNeilBrown dentry->d_op->d_manage(dentry, true) : 0; 109562a7375eSIan Kent } 109662a7375eSIan Kent 10979875cf80SDavid Howells /* 1098287548e4SAl Viro * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if 1099287548e4SAl Viro * we meet a managed dentry that would need blocking. 11009875cf80SDavid Howells */ 11019875cf80SDavid Howells static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, 1102287548e4SAl Viro struct inode **inode) 11039875cf80SDavid Howells { 110462a7375eSIan Kent for (;;) { 1105c7105365SAl Viro struct mount *mounted; 110662a7375eSIan Kent /* 110762a7375eSIan Kent * Don't forget we might have a non-mountpoint managed dentry 110862a7375eSIan Kent * that wants to block transit. 110962a7375eSIan Kent */ 1110b8faf035SNeilBrown switch (managed_dentry_rcu(path->dentry)) { 1111b8faf035SNeilBrown case -ECHILD: 1112b8faf035SNeilBrown default: 1113ab90911fSDavid Howells return false; 1114b8faf035SNeilBrown case -EISDIR: 1115b8faf035SNeilBrown return true; 1116b8faf035SNeilBrown case 0: 1117b8faf035SNeilBrown break; 1118b8faf035SNeilBrown } 111962a7375eSIan Kent 112062a7375eSIan Kent if (!d_mountpoint(path->dentry)) 1121b8faf035SNeilBrown return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 112262a7375eSIan Kent 1123474279dcSAl Viro mounted = __lookup_mnt(path->mnt, path->dentry); 11249875cf80SDavid Howells if (!mounted) 11259875cf80SDavid Howells break; 1126c7105365SAl Viro path->mnt = &mounted->mnt; 1127c7105365SAl Viro path->dentry = mounted->mnt.mnt_root; 1128a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 11299875cf80SDavid Howells nd->seq = read_seqcount_begin(&path->dentry->d_seq); 113059430262SLinus Torvalds /* 113159430262SLinus Torvalds * Update the inode too. We don't need to re-check the 113259430262SLinus Torvalds * dentry sequence number here after this d_inode read, 113359430262SLinus Torvalds * because a mount-point is always pinned. 113459430262SLinus Torvalds */ 113559430262SLinus Torvalds *inode = path->dentry->d_inode; 11369875cf80SDavid Howells } 1137f5be3e29SAl Viro return !read_seqretry(&mount_lock, nd->m_seq) && 1138b8faf035SNeilBrown !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT); 1139287548e4SAl Viro } 1140287548e4SAl Viro 114131e6b01fSNick Piggin static int follow_dotdot_rcu(struct nameidata *nd) 114231e6b01fSNick Piggin { 11434023bfc9SAl Viro struct inode *inode = nd->inode; 11447bd88377SAl Viro if (!nd->root.mnt) 114531e6b01fSNick Piggin set_root_rcu(nd); 114631e6b01fSNick Piggin 114731e6b01fSNick Piggin while (1) { 114831e6b01fSNick Piggin if (nd->path.dentry == nd->root.dentry && 114931e6b01fSNick Piggin nd->path.mnt == nd->root.mnt) { 115031e6b01fSNick Piggin break; 115131e6b01fSNick Piggin } 115231e6b01fSNick Piggin if (nd->path.dentry != nd->path.mnt->mnt_root) { 115331e6b01fSNick Piggin struct dentry *old = nd->path.dentry; 115431e6b01fSNick Piggin struct dentry *parent = old->d_parent; 115531e6b01fSNick Piggin unsigned seq; 115631e6b01fSNick Piggin 11574023bfc9SAl Viro inode = parent->d_inode; 115831e6b01fSNick Piggin seq = read_seqcount_begin(&parent->d_seq); 115931e6b01fSNick Piggin if (read_seqcount_retry(&old->d_seq, nd->seq)) 1160ef7562d5SAl Viro goto failed; 116131e6b01fSNick Piggin nd->path.dentry = parent; 116231e6b01fSNick Piggin nd->seq = seq; 116331e6b01fSNick Piggin break; 116431e6b01fSNick Piggin } 116531e6b01fSNick Piggin if (!follow_up_rcu(&nd->path)) 116631e6b01fSNick Piggin break; 11674023bfc9SAl Viro inode = nd->path.dentry->d_inode; 116831e6b01fSNick Piggin nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 116931e6b01fSNick Piggin } 1170b37199e6SAl Viro while (d_mountpoint(nd->path.dentry)) { 1171b37199e6SAl Viro struct mount *mounted; 1172b37199e6SAl Viro mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry); 1173b37199e6SAl Viro if (!mounted) 1174b37199e6SAl Viro break; 1175b37199e6SAl Viro nd->path.mnt = &mounted->mnt; 1176b37199e6SAl Viro nd->path.dentry = mounted->mnt.mnt_root; 11774023bfc9SAl Viro inode = nd->path.dentry->d_inode; 1178b37199e6SAl Viro nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); 1179f5be3e29SAl Viro if (read_seqretry(&mount_lock, nd->m_seq)) 1180b37199e6SAl Viro goto failed; 1181b37199e6SAl Viro } 11824023bfc9SAl Viro nd->inode = inode; 118331e6b01fSNick Piggin return 0; 1184ef7562d5SAl Viro 1185ef7562d5SAl Viro failed: 1186ef7562d5SAl Viro nd->flags &= ~LOOKUP_RCU; 11875b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1188ef7562d5SAl Viro nd->root.mnt = NULL; 11898b61e74fSAl Viro rcu_read_unlock(); 1190ef7562d5SAl Viro return -ECHILD; 119131e6b01fSNick Piggin } 119231e6b01fSNick Piggin 11939875cf80SDavid Howells /* 1194cc53ce53SDavid Howells * Follow down to the covering mount currently visible to userspace. At each 1195cc53ce53SDavid Howells * point, the filesystem owning that dentry may be queried as to whether the 1196cc53ce53SDavid Howells * caller is permitted to proceed or not. 1197cc53ce53SDavid Howells */ 11987cc90cc3SAl Viro int follow_down(struct path *path) 1199cc53ce53SDavid Howells { 1200cc53ce53SDavid Howells unsigned managed; 1201cc53ce53SDavid Howells int ret; 1202cc53ce53SDavid Howells 1203cc53ce53SDavid Howells while (managed = ACCESS_ONCE(path->dentry->d_flags), 1204cc53ce53SDavid Howells unlikely(managed & DCACHE_MANAGED_DENTRY)) { 1205cc53ce53SDavid Howells /* Allow the filesystem to manage the transit without i_mutex 1206cc53ce53SDavid Howells * being held. 1207cc53ce53SDavid Howells * 1208cc53ce53SDavid Howells * We indicate to the filesystem if someone is trying to mount 1209cc53ce53SDavid Howells * something here. This gives autofs the chance to deny anyone 1210cc53ce53SDavid Howells * other than its daemon the right to mount on its 1211cc53ce53SDavid Howells * superstructure. 1212cc53ce53SDavid Howells * 1213cc53ce53SDavid Howells * The filesystem may sleep at this point. 1214cc53ce53SDavid Howells */ 1215cc53ce53SDavid Howells if (managed & DCACHE_MANAGE_TRANSIT) { 1216cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op); 1217cc53ce53SDavid Howells BUG_ON(!path->dentry->d_op->d_manage); 1218ab90911fSDavid Howells ret = path->dentry->d_op->d_manage( 12191aed3e42SAl Viro path->dentry, false); 1220cc53ce53SDavid Howells if (ret < 0) 1221cc53ce53SDavid Howells return ret == -EISDIR ? 0 : ret; 1222cc53ce53SDavid Howells } 1223cc53ce53SDavid Howells 1224cc53ce53SDavid Howells /* Transit to a mounted filesystem. */ 1225cc53ce53SDavid Howells if (managed & DCACHE_MOUNTED) { 1226cc53ce53SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 1227cc53ce53SDavid Howells if (!mounted) 1228cc53ce53SDavid Howells break; 1229cc53ce53SDavid Howells dput(path->dentry); 1230cc53ce53SDavid Howells mntput(path->mnt); 1231cc53ce53SDavid Howells path->mnt = mounted; 1232cc53ce53SDavid Howells path->dentry = dget(mounted->mnt_root); 1233cc53ce53SDavid Howells continue; 1234cc53ce53SDavid Howells } 1235cc53ce53SDavid Howells 1236cc53ce53SDavid Howells /* Don't handle automount points here */ 1237cc53ce53SDavid Howells break; 1238cc53ce53SDavid Howells } 1239cc53ce53SDavid Howells return 0; 1240cc53ce53SDavid Howells } 12414d359507SAl Viro EXPORT_SYMBOL(follow_down); 1242cc53ce53SDavid Howells 1243cc53ce53SDavid Howells /* 12449875cf80SDavid Howells * Skip to top of mountpoint pile in refwalk mode for follow_dotdot() 12459875cf80SDavid Howells */ 12469875cf80SDavid Howells static void follow_mount(struct path *path) 12479875cf80SDavid Howells { 12489875cf80SDavid Howells while (d_mountpoint(path->dentry)) { 12499875cf80SDavid Howells struct vfsmount *mounted = lookup_mnt(path); 12509875cf80SDavid Howells if (!mounted) 12519875cf80SDavid Howells break; 12529875cf80SDavid Howells dput(path->dentry); 12539875cf80SDavid Howells mntput(path->mnt); 12549875cf80SDavid Howells path->mnt = mounted; 12559875cf80SDavid Howells path->dentry = dget(mounted->mnt_root); 12569875cf80SDavid Howells } 12579875cf80SDavid Howells } 12589875cf80SDavid Howells 125931e6b01fSNick Piggin static void follow_dotdot(struct nameidata *nd) 12601da177e4SLinus Torvalds { 12617bd88377SAl Viro if (!nd->root.mnt) 12622a737871SAl Viro set_root(nd); 1263e518ddb7SAndreas Mohr 12641da177e4SLinus Torvalds while(1) { 12654ac91378SJan Blunck struct dentry *old = nd->path.dentry; 12661da177e4SLinus Torvalds 12672a737871SAl Viro if (nd->path.dentry == nd->root.dentry && 12682a737871SAl Viro nd->path.mnt == nd->root.mnt) { 12691da177e4SLinus Torvalds break; 12701da177e4SLinus Torvalds } 12714ac91378SJan Blunck if (nd->path.dentry != nd->path.mnt->mnt_root) { 12723088dd70SAl Viro /* rare case of legitimate dget_parent()... */ 12733088dd70SAl Viro nd->path.dentry = dget_parent(nd->path.dentry); 12741da177e4SLinus Torvalds dput(old); 12751da177e4SLinus Torvalds break; 12761da177e4SLinus Torvalds } 12773088dd70SAl Viro if (!follow_up(&nd->path)) 12781da177e4SLinus Torvalds break; 12791da177e4SLinus Torvalds } 128079ed0226SAl Viro follow_mount(&nd->path); 128131e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 12821da177e4SLinus Torvalds } 12831da177e4SLinus Torvalds 12841da177e4SLinus Torvalds /* 1285bad61189SMiklos Szeredi * This looks up the name in dcache, possibly revalidates the old dentry and 1286bad61189SMiklos Szeredi * allocates a new one if not found or not valid. In the need_lookup argument 1287bad61189SMiklos Szeredi * returns whether i_op->lookup is necessary. 1288bad61189SMiklos Szeredi * 1289bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 1290baa03890SNick Piggin */ 1291bad61189SMiklos Szeredi static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir, 1292201f956eSAl Viro unsigned int flags, bool *need_lookup) 1293baa03890SNick Piggin { 1294baa03890SNick Piggin struct dentry *dentry; 1295bad61189SMiklos Szeredi int error; 1296baa03890SNick Piggin 1297bad61189SMiklos Szeredi *need_lookup = false; 1298bad61189SMiklos Szeredi dentry = d_lookup(dir, name); 1299bad61189SMiklos Szeredi if (dentry) { 130039e3c955SJeff Layton if (dentry->d_flags & DCACHE_OP_REVALIDATE) { 1301201f956eSAl Viro error = d_revalidate(dentry, flags); 1302bad61189SMiklos Szeredi if (unlikely(error <= 0)) { 1303bad61189SMiklos Szeredi if (error < 0) { 1304bad61189SMiklos Szeredi dput(dentry); 1305bad61189SMiklos Szeredi return ERR_PTR(error); 13065542aa2fSEric W. Biederman } else { 13075542aa2fSEric W. Biederman d_invalidate(dentry); 1308bad61189SMiklos Szeredi dput(dentry); 1309bad61189SMiklos Szeredi dentry = NULL; 1310bad61189SMiklos Szeredi } 1311bad61189SMiklos Szeredi } 1312bad61189SMiklos Szeredi } 1313bad61189SMiklos Szeredi } 1314baa03890SNick Piggin 1315bad61189SMiklos Szeredi if (!dentry) { 1316bad61189SMiklos Szeredi dentry = d_alloc(dir, name); 1317baa03890SNick Piggin if (unlikely(!dentry)) 1318baa03890SNick Piggin return ERR_PTR(-ENOMEM); 1319baa03890SNick Piggin 1320bad61189SMiklos Szeredi *need_lookup = true; 1321baa03890SNick Piggin } 1322baa03890SNick Piggin return dentry; 1323baa03890SNick Piggin } 1324baa03890SNick Piggin 1325baa03890SNick Piggin /* 132613a2c3beSJ. Bruce Fields * Call i_op->lookup on the dentry. The dentry must be negative and 132713a2c3beSJ. Bruce Fields * unhashed. 1328bad61189SMiklos Szeredi * 1329bad61189SMiklos Szeredi * dir->d_inode->i_mutex must be held 133044396f4bSJosef Bacik */ 1331bad61189SMiklos Szeredi static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry, 133272bd866aSAl Viro unsigned int flags) 133344396f4bSJosef Bacik { 133444396f4bSJosef Bacik struct dentry *old; 133544396f4bSJosef Bacik 133644396f4bSJosef Bacik /* Don't create child dentry for a dead directory. */ 1337bad61189SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 1338e188dc02SMiklos Szeredi dput(dentry); 133944396f4bSJosef Bacik return ERR_PTR(-ENOENT); 1340e188dc02SMiklos Szeredi } 134144396f4bSJosef Bacik 134272bd866aSAl Viro old = dir->i_op->lookup(dir, dentry, flags); 134344396f4bSJosef Bacik if (unlikely(old)) { 134444396f4bSJosef Bacik dput(dentry); 134544396f4bSJosef Bacik dentry = old; 134644396f4bSJosef Bacik } 134744396f4bSJosef Bacik return dentry; 134844396f4bSJosef Bacik } 134944396f4bSJosef Bacik 1350a3255546SAl Viro static struct dentry *__lookup_hash(struct qstr *name, 135172bd866aSAl Viro struct dentry *base, unsigned int flags) 1352a3255546SAl Viro { 1353bad61189SMiklos Szeredi bool need_lookup; 1354a3255546SAl Viro struct dentry *dentry; 1355a3255546SAl Viro 135672bd866aSAl Viro dentry = lookup_dcache(name, base, flags, &need_lookup); 1357bad61189SMiklos Szeredi if (!need_lookup) 1358a3255546SAl Viro return dentry; 1359bad61189SMiklos Szeredi 136072bd866aSAl Viro return lookup_real(base->d_inode, dentry, flags); 1361a3255546SAl Viro } 1362a3255546SAl Viro 136344396f4bSJosef Bacik /* 13641da177e4SLinus Torvalds * It's more convoluted than I'd like it to be, but... it's still fairly 13651da177e4SLinus Torvalds * small and for now I'd prefer to have fast path as straight as possible. 13661da177e4SLinus Torvalds * It _is_ time-critical. 13671da177e4SLinus Torvalds */ 1368e97cdc87SAl Viro static int lookup_fast(struct nameidata *nd, 136931e6b01fSNick Piggin struct path *path, struct inode **inode) 13701da177e4SLinus Torvalds { 13714ac91378SJan Blunck struct vfsmount *mnt = nd->path.mnt; 137231e6b01fSNick Piggin struct dentry *dentry, *parent = nd->path.dentry; 13735a18fff2SAl Viro int need_reval = 1; 13745a18fff2SAl Viro int status = 1; 13759875cf80SDavid Howells int err; 13769875cf80SDavid Howells 13773cac260aSAl Viro /* 1378b04f784eSNick Piggin * Rename seqlock is not required here because in the off chance 1379b04f784eSNick Piggin * of a false negative due to a concurrent rename, we're going to 1380b04f784eSNick Piggin * do the non-racy lookup, below. 1381b04f784eSNick Piggin */ 138231e6b01fSNick Piggin if (nd->flags & LOOKUP_RCU) { 138331e6b01fSNick Piggin unsigned seq; 1384766c4cbfSAl Viro bool negative; 1385da53be12SLinus Torvalds dentry = __d_lookup_rcu(parent, &nd->last, &seq); 13865a18fff2SAl Viro if (!dentry) 13875a18fff2SAl Viro goto unlazy; 13885a18fff2SAl Viro 138912f8ad4bSLinus Torvalds /* 139012f8ad4bSLinus Torvalds * This sequence count validates that the inode matches 139112f8ad4bSLinus Torvalds * the dentry name information from lookup. 139212f8ad4bSLinus Torvalds */ 139312f8ad4bSLinus Torvalds *inode = dentry->d_inode; 1394766c4cbfSAl Viro negative = d_is_negative(dentry); 139512f8ad4bSLinus Torvalds if (read_seqcount_retry(&dentry->d_seq, seq)) 139612f8ad4bSLinus Torvalds return -ECHILD; 1397766c4cbfSAl Viro if (negative) 1398766c4cbfSAl Viro return -ENOENT; 139912f8ad4bSLinus Torvalds 140012f8ad4bSLinus Torvalds /* 140112f8ad4bSLinus Torvalds * This sequence count validates that the parent had no 140212f8ad4bSLinus Torvalds * changes while we did the lookup of the dentry above. 140312f8ad4bSLinus Torvalds * 140412f8ad4bSLinus Torvalds * The memory barrier in read_seqcount_begin of child is 140512f8ad4bSLinus Torvalds * enough, we can use __read_seqcount_retry here. 140612f8ad4bSLinus Torvalds */ 140731e6b01fSNick Piggin if (__read_seqcount_retry(&parent->d_seq, nd->seq)) 140831e6b01fSNick Piggin return -ECHILD; 140931e6b01fSNick Piggin nd->seq = seq; 14105a18fff2SAl Viro 141124643087SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) { 14124ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14135a18fff2SAl Viro if (unlikely(status <= 0)) { 14145a18fff2SAl Viro if (status != -ECHILD) 14155a18fff2SAl Viro need_reval = 0; 14165a18fff2SAl Viro goto unlazy; 14175a18fff2SAl Viro } 141824643087SAl Viro } 141931e6b01fSNick Piggin path->mnt = mnt; 142031e6b01fSNick Piggin path->dentry = dentry; 1421b8faf035SNeilBrown if (likely(__follow_mount_rcu(nd, path, inode))) 14229875cf80SDavid Howells return 0; 14235a18fff2SAl Viro unlazy: 142419660af7SAl Viro if (unlazy_walk(nd, dentry)) 14255a18fff2SAl Viro return -ECHILD; 14265a18fff2SAl Viro } else { 1427e97cdc87SAl Viro dentry = __d_lookup(parent, &nd->last); 142824643087SAl Viro } 14295a18fff2SAl Viro 143081e6f520SAl Viro if (unlikely(!dentry)) 143181e6f520SAl Viro goto need_lookup; 14325a18fff2SAl Viro 14335a18fff2SAl Viro if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval) 14344ce16ef3SAl Viro status = d_revalidate(dentry, nd->flags); 14355a18fff2SAl Viro if (unlikely(status <= 0)) { 14365a18fff2SAl Viro if (status < 0) { 14375a18fff2SAl Viro dput(dentry); 14385a18fff2SAl Viro return status; 14395a18fff2SAl Viro } 14405542aa2fSEric W. Biederman d_invalidate(dentry); 14415a18fff2SAl Viro dput(dentry); 144281e6f520SAl Viro goto need_lookup; 14435a18fff2SAl Viro } 1444697f514dSMiklos Szeredi 1445766c4cbfSAl Viro if (unlikely(d_is_negative(dentry))) { 1446766c4cbfSAl Viro dput(dentry); 1447766c4cbfSAl Viro return -ENOENT; 1448766c4cbfSAl Viro } 14491da177e4SLinus Torvalds path->mnt = mnt; 14501da177e4SLinus Torvalds path->dentry = dentry; 14519875cf80SDavid Howells err = follow_managed(path, nd->flags); 145289312214SIan Kent if (unlikely(err < 0)) { 145389312214SIan Kent path_put_conditional(path, nd); 14549875cf80SDavid Howells return err; 145589312214SIan Kent } 1456a3fbbde7SAl Viro if (err) 1457a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 145831e6b01fSNick Piggin *inode = path->dentry->d_inode; 14591da177e4SLinus Torvalds return 0; 146081e6f520SAl Viro 146181e6f520SAl Viro need_lookup: 1462697f514dSMiklos Szeredi return 1; 1463697f514dSMiklos Szeredi } 1464697f514dSMiklos Szeredi 1465697f514dSMiklos Szeredi /* Fast lookup failed, do it the slow way */ 1466cc2a5271SAl Viro static int lookup_slow(struct nameidata *nd, struct path *path) 1467697f514dSMiklos Szeredi { 1468697f514dSMiklos Szeredi struct dentry *dentry, *parent; 1469697f514dSMiklos Szeredi int err; 1470697f514dSMiklos Szeredi 1471697f514dSMiklos Szeredi parent = nd->path.dentry; 147281e6f520SAl Viro BUG_ON(nd->inode != parent->d_inode); 147381e6f520SAl Viro 147481e6f520SAl Viro mutex_lock(&parent->d_inode->i_mutex); 1475cc2a5271SAl Viro dentry = __lookup_hash(&nd->last, parent, nd->flags); 147681e6f520SAl Viro mutex_unlock(&parent->d_inode->i_mutex); 147781e6f520SAl Viro if (IS_ERR(dentry)) 147881e6f520SAl Viro return PTR_ERR(dentry); 1479697f514dSMiklos Szeredi path->mnt = nd->path.mnt; 1480697f514dSMiklos Szeredi path->dentry = dentry; 1481697f514dSMiklos Szeredi err = follow_managed(path, nd->flags); 1482697f514dSMiklos Szeredi if (unlikely(err < 0)) { 1483697f514dSMiklos Szeredi path_put_conditional(path, nd); 1484697f514dSMiklos Szeredi return err; 1485697f514dSMiklos Szeredi } 1486697f514dSMiklos Szeredi if (err) 1487697f514dSMiklos Szeredi nd->flags |= LOOKUP_JUMPED; 1488697f514dSMiklos Szeredi return 0; 14891da177e4SLinus Torvalds } 14901da177e4SLinus Torvalds 149152094c8aSAl Viro static inline int may_lookup(struct nameidata *nd) 149252094c8aSAl Viro { 149352094c8aSAl Viro if (nd->flags & LOOKUP_RCU) { 14944ad5abb3SAl Viro int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK); 149552094c8aSAl Viro if (err != -ECHILD) 149652094c8aSAl Viro return err; 149719660af7SAl Viro if (unlazy_walk(nd, NULL)) 149852094c8aSAl Viro return -ECHILD; 149952094c8aSAl Viro } 15004ad5abb3SAl Viro return inode_permission(nd->inode, MAY_EXEC); 150152094c8aSAl Viro } 150252094c8aSAl Viro 15039856fa1bSAl Viro static inline int handle_dots(struct nameidata *nd, int type) 15049856fa1bSAl Viro { 15059856fa1bSAl Viro if (type == LAST_DOTDOT) { 15069856fa1bSAl Viro if (nd->flags & LOOKUP_RCU) { 15079856fa1bSAl Viro if (follow_dotdot_rcu(nd)) 15089856fa1bSAl Viro return -ECHILD; 15099856fa1bSAl Viro } else 15109856fa1bSAl Viro follow_dotdot(nd); 15119856fa1bSAl Viro } 15129856fa1bSAl Viro return 0; 15139856fa1bSAl Viro } 15149856fa1bSAl Viro 1515951361f9SAl Viro static void terminate_walk(struct nameidata *nd) 1516951361f9SAl Viro { 1517951361f9SAl Viro if (!(nd->flags & LOOKUP_RCU)) { 1518951361f9SAl Viro path_put(&nd->path); 1519951361f9SAl Viro } else { 1520951361f9SAl Viro nd->flags &= ~LOOKUP_RCU; 15215b6ca027SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 1522951361f9SAl Viro nd->root.mnt = NULL; 15238b61e74fSAl Viro rcu_read_unlock(); 1524951361f9SAl Viro } 1525951361f9SAl Viro } 1526951361f9SAl Viro 15273ddcd056SLinus Torvalds /* 15283ddcd056SLinus Torvalds * Do we need to follow links? We _really_ want to be able 15293ddcd056SLinus Torvalds * to do this check without having to look at inode->i_op, 15303ddcd056SLinus Torvalds * so we keep a cache of "no, this doesn't need follow_link" 15313ddcd056SLinus Torvalds * for the common case. 15323ddcd056SLinus Torvalds */ 1533b18825a7SDavid Howells static inline int should_follow_link(struct dentry *dentry, int follow) 15343ddcd056SLinus Torvalds { 1535b18825a7SDavid Howells return unlikely(d_is_symlink(dentry)) ? follow : 0; 15363ddcd056SLinus Torvalds } 15373ddcd056SLinus Torvalds 1538caa85634SAl Viro static int walk_component(struct nameidata *nd, int follow) 1539ce57dfc1SAl Viro { 1540caa85634SAl Viro struct path path; 1541ce57dfc1SAl Viro struct inode *inode; 1542ce57dfc1SAl Viro int err; 1543ce57dfc1SAl Viro /* 1544ce57dfc1SAl Viro * "." and ".." are special - ".." especially so because it has 1545ce57dfc1SAl Viro * to be able to know about the current root directory and 1546ce57dfc1SAl Viro * parent relationships. 1547ce57dfc1SAl Viro */ 154821b9b073SAl Viro if (unlikely(nd->last_type != LAST_NORM)) 154921b9b073SAl Viro return handle_dots(nd, nd->last_type); 1550caa85634SAl Viro err = lookup_fast(nd, &path, &inode); 1551ce57dfc1SAl Viro if (unlikely(err)) { 1552697f514dSMiklos Szeredi if (err < 0) 1553697f514dSMiklos Szeredi goto out_err; 1554697f514dSMiklos Szeredi 1555caa85634SAl Viro err = lookup_slow(nd, &path); 1556697f514dSMiklos Szeredi if (err < 0) 1557697f514dSMiklos Szeredi goto out_err; 1558697f514dSMiklos Szeredi 1559caa85634SAl Viro inode = path.dentry->d_inode; 1560697f514dSMiklos Szeredi err = -ENOENT; 1561caa85634SAl Viro if (d_is_negative(path.dentry)) 1562697f514dSMiklos Szeredi goto out_path_put; 1563766c4cbfSAl Viro } 1564697f514dSMiklos Szeredi 1565caa85634SAl Viro if (should_follow_link(path.dentry, follow)) { 156619660af7SAl Viro if (nd->flags & LOOKUP_RCU) { 1567caa85634SAl Viro if (unlikely(nd->path.mnt != path.mnt || 1568caa85634SAl Viro unlazy_walk(nd, path.dentry))) { 1569697f514dSMiklos Szeredi err = -ECHILD; 1570697f514dSMiklos Szeredi goto out_err; 157119660af7SAl Viro } 157219660af7SAl Viro } 1573caa85634SAl Viro BUG_ON(inode != path.dentry->d_inode); 1574caa85634SAl Viro nd->link = path; 1575ce57dfc1SAl Viro return 1; 1576ce57dfc1SAl Viro } 1577caa85634SAl Viro path_to_nameidata(&path, nd); 1578ce57dfc1SAl Viro nd->inode = inode; 1579ce57dfc1SAl Viro return 0; 1580697f514dSMiklos Szeredi 1581697f514dSMiklos Szeredi out_path_put: 1582caa85634SAl Viro path_to_nameidata(&path, nd); 1583697f514dSMiklos Szeredi out_err: 1584697f514dSMiklos Szeredi terminate_walk(nd); 1585697f514dSMiklos Szeredi return err; 1586ce57dfc1SAl Viro } 1587ce57dfc1SAl Viro 15881da177e4SLinus Torvalds /* 1589bfcfaa77SLinus Torvalds * We can do the critical dentry name comparison and hashing 1590bfcfaa77SLinus Torvalds * operations one word at a time, but we are limited to: 1591bfcfaa77SLinus Torvalds * 1592bfcfaa77SLinus Torvalds * - Architectures with fast unaligned word accesses. We could 1593bfcfaa77SLinus Torvalds * do a "get_unaligned()" if this helps and is sufficiently 1594bfcfaa77SLinus Torvalds * fast. 1595bfcfaa77SLinus Torvalds * 1596bfcfaa77SLinus Torvalds * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we 1597bfcfaa77SLinus Torvalds * do not trap on the (extremely unlikely) case of a page 1598bfcfaa77SLinus Torvalds * crossing operation. 1599bfcfaa77SLinus Torvalds * 1600bfcfaa77SLinus Torvalds * - Furthermore, we need an efficient 64-bit compile for the 1601bfcfaa77SLinus Torvalds * 64-bit case in order to generate the "number of bytes in 1602bfcfaa77SLinus Torvalds * the final mask". Again, that could be replaced with a 1603bfcfaa77SLinus Torvalds * efficient population count instruction or similar. 1604bfcfaa77SLinus Torvalds */ 1605bfcfaa77SLinus Torvalds #ifdef CONFIG_DCACHE_WORD_ACCESS 1606bfcfaa77SLinus Torvalds 1607f68e556eSLinus Torvalds #include <asm/word-at-a-time.h> 1608bfcfaa77SLinus Torvalds 1609f68e556eSLinus Torvalds #ifdef CONFIG_64BIT 1610bfcfaa77SLinus Torvalds 1611bfcfaa77SLinus Torvalds static inline unsigned int fold_hash(unsigned long hash) 1612bfcfaa77SLinus Torvalds { 161399d263d4SLinus Torvalds return hash_64(hash, 32); 1614bfcfaa77SLinus Torvalds } 1615bfcfaa77SLinus Torvalds 1616bfcfaa77SLinus Torvalds #else /* 32-bit case */ 1617bfcfaa77SLinus Torvalds 1618bfcfaa77SLinus Torvalds #define fold_hash(x) (x) 1619bfcfaa77SLinus Torvalds 1620bfcfaa77SLinus Torvalds #endif 1621bfcfaa77SLinus Torvalds 1622bfcfaa77SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 1623bfcfaa77SLinus Torvalds { 1624bfcfaa77SLinus Torvalds unsigned long a, mask; 1625bfcfaa77SLinus Torvalds unsigned long hash = 0; 1626bfcfaa77SLinus Torvalds 1627bfcfaa77SLinus Torvalds for (;;) { 1628e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name); 1629bfcfaa77SLinus Torvalds if (len < sizeof(unsigned long)) 1630bfcfaa77SLinus Torvalds break; 1631bfcfaa77SLinus Torvalds hash += a; 1632f132c5beSAl Viro hash *= 9; 1633bfcfaa77SLinus Torvalds name += sizeof(unsigned long); 1634bfcfaa77SLinus Torvalds len -= sizeof(unsigned long); 1635bfcfaa77SLinus Torvalds if (!len) 1636bfcfaa77SLinus Torvalds goto done; 1637bfcfaa77SLinus Torvalds } 1638a5c21dceSWill Deacon mask = bytemask_from_count(len); 1639bfcfaa77SLinus Torvalds hash += mask & a; 1640bfcfaa77SLinus Torvalds done: 1641bfcfaa77SLinus Torvalds return fold_hash(hash); 1642bfcfaa77SLinus Torvalds } 1643bfcfaa77SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 1644bfcfaa77SLinus Torvalds 1645bfcfaa77SLinus Torvalds /* 1646bfcfaa77SLinus Torvalds * Calculate the length and hash of the path component, and 1647d6bb3e90SLinus Torvalds * return the "hash_len" as the result. 1648bfcfaa77SLinus Torvalds */ 1649d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1650bfcfaa77SLinus Torvalds { 165136126f8fSLinus Torvalds unsigned long a, b, adata, bdata, mask, hash, len; 165236126f8fSLinus Torvalds const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; 1653bfcfaa77SLinus Torvalds 1654bfcfaa77SLinus Torvalds hash = a = 0; 1655bfcfaa77SLinus Torvalds len = -sizeof(unsigned long); 1656bfcfaa77SLinus Torvalds do { 1657bfcfaa77SLinus Torvalds hash = (hash + a) * 9; 1658bfcfaa77SLinus Torvalds len += sizeof(unsigned long); 1659e419b4ccSLinus Torvalds a = load_unaligned_zeropad(name+len); 166036126f8fSLinus Torvalds b = a ^ REPEAT_BYTE('/'); 166136126f8fSLinus Torvalds } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants))); 1662bfcfaa77SLinus Torvalds 166336126f8fSLinus Torvalds adata = prep_zero_mask(a, adata, &constants); 166436126f8fSLinus Torvalds bdata = prep_zero_mask(b, bdata, &constants); 166536126f8fSLinus Torvalds 166636126f8fSLinus Torvalds mask = create_zero_mask(adata | bdata); 166736126f8fSLinus Torvalds 166836126f8fSLinus Torvalds hash += a & zero_bytemask(mask); 16699226b5b4SLinus Torvalds len += find_zero(mask); 1670d6bb3e90SLinus Torvalds return hashlen_create(fold_hash(hash), len); 1671bfcfaa77SLinus Torvalds } 1672bfcfaa77SLinus Torvalds 1673bfcfaa77SLinus Torvalds #else 1674bfcfaa77SLinus Torvalds 16750145acc2SLinus Torvalds unsigned int full_name_hash(const unsigned char *name, unsigned int len) 16760145acc2SLinus Torvalds { 16770145acc2SLinus Torvalds unsigned long hash = init_name_hash(); 16780145acc2SLinus Torvalds while (len--) 16790145acc2SLinus Torvalds hash = partial_name_hash(*name++, hash); 16800145acc2SLinus Torvalds return end_name_hash(hash); 16810145acc2SLinus Torvalds } 1682ae942ae7SLinus Torvalds EXPORT_SYMBOL(full_name_hash); 16830145acc2SLinus Torvalds 16843ddcd056SLinus Torvalds /* 1685200e9ef7SLinus Torvalds * We know there's a real path component here of at least 1686200e9ef7SLinus Torvalds * one character. 1687200e9ef7SLinus Torvalds */ 1688d6bb3e90SLinus Torvalds static inline u64 hash_name(const char *name) 1689200e9ef7SLinus Torvalds { 1690200e9ef7SLinus Torvalds unsigned long hash = init_name_hash(); 1691200e9ef7SLinus Torvalds unsigned long len = 0, c; 1692200e9ef7SLinus Torvalds 1693200e9ef7SLinus Torvalds c = (unsigned char)*name; 1694200e9ef7SLinus Torvalds do { 1695200e9ef7SLinus Torvalds len++; 1696200e9ef7SLinus Torvalds hash = partial_name_hash(c, hash); 1697200e9ef7SLinus Torvalds c = (unsigned char)name[len]; 1698200e9ef7SLinus Torvalds } while (c && c != '/'); 1699d6bb3e90SLinus Torvalds return hashlen_create(end_name_hash(hash), len); 1700200e9ef7SLinus Torvalds } 1701200e9ef7SLinus Torvalds 1702bfcfaa77SLinus Torvalds #endif 1703bfcfaa77SLinus Torvalds 1704200e9ef7SLinus Torvalds /* 17051da177e4SLinus Torvalds * Name resolution. 1706ea3834d9SPrasanna Meda * This is the basic name resolution function, turning a pathname into 1707ea3834d9SPrasanna Meda * the final dentry. We expect 'base' to be positive and a directory. 17081da177e4SLinus Torvalds * 1709ea3834d9SPrasanna Meda * Returns 0 and nd will have valid dentry and mnt on success. 1710ea3834d9SPrasanna Meda * Returns error and drops reference to input namei data on failure. 17111da177e4SLinus Torvalds */ 17126de88d72SAl Viro static int link_path_walk(const char *name, struct nameidata *nd) 17131da177e4SLinus Torvalds { 171432cd7468SAl Viro struct saved { 171532cd7468SAl Viro struct path link; 171632cd7468SAl Viro void *cookie; 171732cd7468SAl Viro const char *name; 171832cd7468SAl Viro } stack[MAX_NESTED_LINKS], *last = stack + nd->depth - 1; 17191da177e4SLinus Torvalds int err; 17201da177e4SLinus Torvalds 17211da177e4SLinus Torvalds while (*name=='/') 17221da177e4SLinus Torvalds name++; 17231da177e4SLinus Torvalds if (!*name) 17249e18f10aSAl Viro return 0; 17251da177e4SLinus Torvalds 17261da177e4SLinus Torvalds /* At this point we know we have a real path component. */ 17271da177e4SLinus Torvalds for(;;) { 1728d6bb3e90SLinus Torvalds u64 hash_len; 1729fe479a58SAl Viro int type; 17301da177e4SLinus Torvalds 173152094c8aSAl Viro err = may_lookup(nd); 17321da177e4SLinus Torvalds if (err) 17331da177e4SLinus Torvalds break; 17341da177e4SLinus Torvalds 1735d6bb3e90SLinus Torvalds hash_len = hash_name(name); 17361da177e4SLinus Torvalds 1737fe479a58SAl Viro type = LAST_NORM; 1738d6bb3e90SLinus Torvalds if (name[0] == '.') switch (hashlen_len(hash_len)) { 1739fe479a58SAl Viro case 2: 1740200e9ef7SLinus Torvalds if (name[1] == '.') { 1741fe479a58SAl Viro type = LAST_DOTDOT; 174216c2cd71SAl Viro nd->flags |= LOOKUP_JUMPED; 174316c2cd71SAl Viro } 1744fe479a58SAl Viro break; 1745fe479a58SAl Viro case 1: 1746fe479a58SAl Viro type = LAST_DOT; 1747fe479a58SAl Viro } 17485a202bcdSAl Viro if (likely(type == LAST_NORM)) { 17495a202bcdSAl Viro struct dentry *parent = nd->path.dentry; 175016c2cd71SAl Viro nd->flags &= ~LOOKUP_JUMPED; 17515a202bcdSAl Viro if (unlikely(parent->d_flags & DCACHE_OP_HASH)) { 1752a060dc50SJames Hogan struct qstr this = { { .hash_len = hash_len }, .name = name }; 1753da53be12SLinus Torvalds err = parent->d_op->d_hash(parent, &this); 17545a202bcdSAl Viro if (err < 0) 17555a202bcdSAl Viro break; 1756d6bb3e90SLinus Torvalds hash_len = this.hash_len; 1757d6bb3e90SLinus Torvalds name = this.name; 17585a202bcdSAl Viro } 17595a202bcdSAl Viro } 1760fe479a58SAl Viro 1761d6bb3e90SLinus Torvalds nd->last.hash_len = hash_len; 1762d6bb3e90SLinus Torvalds nd->last.name = name; 17635f4a6a69SAl Viro nd->last_type = type; 17645f4a6a69SAl Viro 1765d6bb3e90SLinus Torvalds name += hashlen_len(hash_len); 1766d6bb3e90SLinus Torvalds if (!*name) 1767bdf6cbf1SAl Viro goto OK; 1768200e9ef7SLinus Torvalds /* 1769200e9ef7SLinus Torvalds * If it wasn't NUL, we know it was '/'. Skip that 1770200e9ef7SLinus Torvalds * slash, and continue until no more slashes. 1771200e9ef7SLinus Torvalds */ 1772200e9ef7SLinus Torvalds do { 1773d6bb3e90SLinus Torvalds name++; 1774d6bb3e90SLinus Torvalds } while (unlikely(*name == '/')); 1775d6bb3e90SLinus Torvalds if (!*name) 1776bdf6cbf1SAl Viro goto OK; 17775f4a6a69SAl Viro 1778caa85634SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 1779bb8603f8SAl Viro Walked: 1780ce57dfc1SAl Viro if (err < 0) 1781bdf6cbf1SAl Viro goto Err; 1782fe479a58SAl Viro 1783ce57dfc1SAl Viro if (err) { 1784d40bcc09SAl Viro const char *s; 1785d40bcc09SAl Viro 17865a460275SAl Viro if (unlikely(current->link_count >= MAX_NESTED_LINKS)) { 17875a460275SAl Viro path_put_conditional(&nd->link, nd); 17885a460275SAl Viro path_put(&nd->path); 1789bdf6cbf1SAl Viro err = -ELOOP; 1790bdf6cbf1SAl Viro goto Err; 17915a460275SAl Viro } 17925a460275SAl Viro BUG_ON(nd->depth >= MAX_NESTED_LINKS); 17935a460275SAl Viro 17945a460275SAl Viro nd->depth++; 17955a460275SAl Viro current->link_count++; 179632cd7468SAl Viro last++; 17975a460275SAl Viro 179832cd7468SAl Viro last->link = nd->link; 179932cd7468SAl Viro s = get_link(&last->link, nd, &last->cookie); 18005a460275SAl Viro 1801172a39a0SAl Viro if (unlikely(IS_ERR(s))) { 1802172a39a0SAl Viro err = PTR_ERR(s); 1803b0c24c3bSAl Viro current->link_count--; 1804b0c24c3bSAl Viro nd->depth--; 180532cd7468SAl Viro last--; 1806bdf6cbf1SAl Viro goto Err; 1807172a39a0SAl Viro } 1808172a39a0SAl Viro err = 0; 180912b09578SAl Viro if (unlikely(!s)) { 181012b09578SAl Viro /* jumped */ 181132cd7468SAl Viro put_link(nd, &last->link, last->cookie); 181248c8b0c5SAl Viro current->link_count--; 181348c8b0c5SAl Viro nd->depth--; 181432cd7468SAl Viro last--; 181512b09578SAl Viro } else { 1816172a39a0SAl Viro if (*s == '/') { 1817172a39a0SAl Viro if (!nd->root.mnt) 1818172a39a0SAl Viro set_root(nd); 1819172a39a0SAl Viro path_put(&nd->path); 1820172a39a0SAl Viro nd->path = nd->root; 1821172a39a0SAl Viro path_get(&nd->root); 1822172a39a0SAl Viro nd->flags |= LOOKUP_JUMPED; 18239e18f10aSAl Viro while (unlikely(*++s == '/')) 18249e18f10aSAl Viro ; 1825172a39a0SAl Viro } 1826172a39a0SAl Viro nd->inode = nd->path.dentry->d_inode; 182732cd7468SAl Viro last->name = name; 18289e18f10aSAl Viro if (!*s) 18299e18f10aSAl Viro goto OK; 183032cd7468SAl Viro name = s; 18319e18f10aSAl Viro continue; 183248c8b0c5SAl Viro } 183331e6b01fSNick Piggin } 183444b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 18353ddcd056SLinus Torvalds err = -ENOTDIR; 18363ddcd056SLinus Torvalds break; 18375f4a6a69SAl Viro } 1838ce57dfc1SAl Viro } 1839951361f9SAl Viro terminate_walk(nd); 1840bdf6cbf1SAl Viro Err: 184107681481SAl Viro while (unlikely(nd->depth)) { 184207681481SAl Viro put_link(nd, &last->link, last->cookie); 184307681481SAl Viro current->link_count--; 184407681481SAl Viro nd->depth--; 184507681481SAl Viro last--; 184607681481SAl Viro } 18471da177e4SLinus Torvalds return err; 1848bdf6cbf1SAl Viro OK: 184907681481SAl Viro if (unlikely(nd->depth)) { 185007681481SAl Viro name = last->name; 185107681481SAl Viro err = walk_component(nd, LOOKUP_FOLLOW); 185207681481SAl Viro put_link(nd, &last->link, last->cookie); 185307681481SAl Viro current->link_count--; 185407681481SAl Viro nd->depth--; 185507681481SAl Viro last--; 185607681481SAl Viro goto Walked; 185707681481SAl Viro } 1858bdf6cbf1SAl Viro return 0; 18591da177e4SLinus Torvalds } 18601da177e4SLinus Torvalds 18616e8a1f87SAl Viro static int path_init(int dfd, const struct filename *name, unsigned int flags, 18625e53084dSAl Viro struct nameidata *nd) 186331e6b01fSNick Piggin { 186431e6b01fSNick Piggin int retval = 0; 1865fd2f7cb5SAl Viro const char *s = name->name; 186631e6b01fSNick Piggin 186731e6b01fSNick Piggin nd->last_type = LAST_ROOT; /* if there are only slashes... */ 1868980f3ea2SAl Viro nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT; 186931e6b01fSNick Piggin nd->depth = 0; 18705e53084dSAl Viro nd->base = NULL; 18715b6ca027SAl Viro if (flags & LOOKUP_ROOT) { 1872b18825a7SDavid Howells struct dentry *root = nd->root.dentry; 1873b18825a7SDavid Howells struct inode *inode = root->d_inode; 1874fd2f7cb5SAl Viro if (*s) { 187544b1d530SMiklos Szeredi if (!d_can_lookup(root)) 18765b6ca027SAl Viro return -ENOTDIR; 18775b6ca027SAl Viro retval = inode_permission(inode, MAY_EXEC); 18785b6ca027SAl Viro if (retval) 18795b6ca027SAl Viro return retval; 188073d049a4SAl Viro } 18815b6ca027SAl Viro nd->path = nd->root; 18825b6ca027SAl Viro nd->inode = inode; 18835b6ca027SAl Viro if (flags & LOOKUP_RCU) { 18848b61e74fSAl Viro rcu_read_lock(); 18855b6ca027SAl Viro nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 188648a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 18875b6ca027SAl Viro } else { 18885b6ca027SAl Viro path_get(&nd->path); 18895b6ca027SAl Viro } 1890d465887fSAl Viro goto done; 18915b6ca027SAl Viro } 18925b6ca027SAl Viro 189331e6b01fSNick Piggin nd->root.mnt = NULL; 189431e6b01fSNick Piggin 189548a066e7SAl Viro nd->m_seq = read_seqbegin(&mount_lock); 1896fd2f7cb5SAl Viro if (*s == '/') { 1897e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 18988b61e74fSAl Viro rcu_read_lock(); 18997bd88377SAl Viro nd->seq = set_root_rcu(nd); 1900e41f7d4eSAl Viro } else { 1901e41f7d4eSAl Viro set_root(nd); 1902e41f7d4eSAl Viro path_get(&nd->root); 1903e41f7d4eSAl Viro } 190431e6b01fSNick Piggin nd->path = nd->root; 190531e6b01fSNick Piggin } else if (dfd == AT_FDCWD) { 1906e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 190731e6b01fSNick Piggin struct fs_struct *fs = current->fs; 1908c28cc364SNick Piggin unsigned seq; 190931e6b01fSNick Piggin 19108b61e74fSAl Viro rcu_read_lock(); 191131e6b01fSNick Piggin 1912c28cc364SNick Piggin do { 1913c28cc364SNick Piggin seq = read_seqcount_begin(&fs->seq); 191431e6b01fSNick Piggin nd->path = fs->pwd; 1915c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 1916c28cc364SNick Piggin } while (read_seqcount_retry(&fs->seq, seq)); 1917e41f7d4eSAl Viro } else { 1918e41f7d4eSAl Viro get_fs_pwd(current->fs, &nd->path); 1919e41f7d4eSAl Viro } 192031e6b01fSNick Piggin } else { 1921582aa64aSJeff Layton /* Caller must check execute permissions on the starting path component */ 19222903ff01SAl Viro struct fd f = fdget_raw(dfd); 192331e6b01fSNick Piggin struct dentry *dentry; 192431e6b01fSNick Piggin 19252903ff01SAl Viro if (!f.file) 19262903ff01SAl Viro return -EBADF; 192731e6b01fSNick Piggin 19282903ff01SAl Viro dentry = f.file->f_path.dentry; 192931e6b01fSNick Piggin 1930fd2f7cb5SAl Viro if (*s) { 193144b1d530SMiklos Szeredi if (!d_can_lookup(dentry)) { 19322903ff01SAl Viro fdput(f); 19332903ff01SAl Viro return -ENOTDIR; 1934f52e0c11SAl Viro } 19352903ff01SAl Viro } 19362903ff01SAl Viro 19372903ff01SAl Viro nd->path = f.file->f_path; 1938e41f7d4eSAl Viro if (flags & LOOKUP_RCU) { 19399c225f26SLinus Torvalds if (f.flags & FDPUT_FPUT) 19405e53084dSAl Viro nd->base = f.file; 1941c28cc364SNick Piggin nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); 19428b61e74fSAl Viro rcu_read_lock(); 19435590ff0dSUlrich Drepper } else { 19442903ff01SAl Viro path_get(&nd->path); 19452903ff01SAl Viro fdput(f); 19461da177e4SLinus Torvalds } 1947e41f7d4eSAl Viro } 1948e41f7d4eSAl Viro 194931e6b01fSNick Piggin nd->inode = nd->path.dentry->d_inode; 19504023bfc9SAl Viro if (!(flags & LOOKUP_RCU)) 1951d465887fSAl Viro goto done; 19524023bfc9SAl Viro if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq))) 1953d465887fSAl Viro goto done; 19544023bfc9SAl Viro if (!(nd->flags & LOOKUP_ROOT)) 19554023bfc9SAl Viro nd->root.mnt = NULL; 19564023bfc9SAl Viro rcu_read_unlock(); 19574023bfc9SAl Viro return -ECHILD; 1958d465887fSAl Viro done: 1959d465887fSAl Viro current->total_link_count = 0; 1960fd2f7cb5SAl Viro return link_path_walk(s, nd); 19619b4a9b14SAl Viro } 19629b4a9b14SAl Viro 1963893b7775SAl Viro static void path_cleanup(struct nameidata *nd) 1964893b7775SAl Viro { 1965893b7775SAl Viro if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) { 1966893b7775SAl Viro path_put(&nd->root); 1967893b7775SAl Viro nd->root.mnt = NULL; 1968893b7775SAl Viro } 1969893b7775SAl Viro if (unlikely(nd->base)) 1970893b7775SAl Viro fput(nd->base); 19719b4a9b14SAl Viro } 19729b4a9b14SAl Viro 197395fa25d9SAl Viro static int trailing_symlink(struct path *link, struct nameidata *nd, void **p) 197495fa25d9SAl Viro { 197595fa25d9SAl Viro const char *s; 197695fa25d9SAl Viro int error = may_follow_link(link, nd); 197795fa25d9SAl Viro if (unlikely(error)) 197895fa25d9SAl Viro return error; 197995fa25d9SAl Viro nd->flags |= LOOKUP_PARENT; 198095fa25d9SAl Viro s = get_link(link, nd, p); 198195fa25d9SAl Viro if (unlikely(IS_ERR(s))) 198295fa25d9SAl Viro return PTR_ERR(s); 198395fa25d9SAl Viro if (unlikely(!s)) 198495fa25d9SAl Viro return 0; 198595fa25d9SAl Viro if (*s == '/') { 198695fa25d9SAl Viro if (!nd->root.mnt) 198795fa25d9SAl Viro set_root(nd); 198895fa25d9SAl Viro path_put(&nd->path); 198995fa25d9SAl Viro nd->path = nd->root; 199095fa25d9SAl Viro path_get(&nd->root); 199195fa25d9SAl Viro nd->flags |= LOOKUP_JUMPED; 199295fa25d9SAl Viro } 199395fa25d9SAl Viro nd->inode = nd->path.dentry->d_inode; 199495fa25d9SAl Viro error = link_path_walk(s, nd); 199595fa25d9SAl Viro if (unlikely(error)) 199695fa25d9SAl Viro put_link(nd, link, *p); 199795fa25d9SAl Viro return error; 199895fa25d9SAl Viro } 199995fa25d9SAl Viro 2000caa85634SAl Viro static inline int lookup_last(struct nameidata *nd) 2001bd92d7feSAl Viro { 2002bd92d7feSAl Viro if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len]) 2003bd92d7feSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2004bd92d7feSAl Viro 2005bd92d7feSAl Viro nd->flags &= ~LOOKUP_PARENT; 2006caa85634SAl Viro return walk_component(nd, nd->flags & LOOKUP_FOLLOW); 2007bd92d7feSAl Viro } 2008bd92d7feSAl Viro 20099b4a9b14SAl Viro /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */ 20105eb6b495SAl Viro static int path_lookupat(int dfd, const struct filename *name, 20119b4a9b14SAl Viro unsigned int flags, struct nameidata *nd) 20129b4a9b14SAl Viro { 2013bd92d7feSAl Viro int err; 201431e6b01fSNick Piggin 201531e6b01fSNick Piggin /* 201631e6b01fSNick Piggin * Path walking is largely split up into 2 different synchronisation 201731e6b01fSNick Piggin * schemes, rcu-walk and ref-walk (explained in 201831e6b01fSNick Piggin * Documentation/filesystems/path-lookup.txt). These share much of the 201931e6b01fSNick Piggin * path walk code, but some things particularly setup, cleanup, and 202031e6b01fSNick Piggin * following mounts are sufficiently divergent that functions are 202131e6b01fSNick Piggin * duplicated. Typically there is a function foo(), and its RCU 202231e6b01fSNick Piggin * analogue, foo_rcu(). 202331e6b01fSNick Piggin * 202431e6b01fSNick Piggin * -ECHILD is the error number of choice (just to avoid clashes) that 202531e6b01fSNick Piggin * is returned if some aspect of an rcu-walk fails. Such an error must 202631e6b01fSNick Piggin * be handled by restarting a traditional ref-walk (which will always 202731e6b01fSNick Piggin * be able to complete). 202831e6b01fSNick Piggin */ 20296e8a1f87SAl Viro err = path_init(dfd, name, flags, nd); 2030bd92d7feSAl Viro if (!err && !(flags & LOOKUP_PARENT)) { 2031caa85634SAl Viro err = lookup_last(nd); 2032bd92d7feSAl Viro while (err > 0) { 2033bd92d7feSAl Viro void *cookie; 2034caa85634SAl Viro struct path link = nd->link; 203595fa25d9SAl Viro err = trailing_symlink(&link, nd, &cookie); 20366d7b5aaeSAl Viro if (err) 20376d7b5aaeSAl Viro break; 2038caa85634SAl Viro err = lookup_last(nd); 2039574197e0SAl Viro put_link(nd, &link, cookie); 2040bd92d7feSAl Viro } 2041bd92d7feSAl Viro } 2042ee0827cdSAl Viro 20439f1fafeeSAl Viro if (!err) 20449f1fafeeSAl Viro err = complete_walk(nd); 2045bd92d7feSAl Viro 2046bd92d7feSAl Viro if (!err && nd->flags & LOOKUP_DIRECTORY) { 204744b1d530SMiklos Szeredi if (!d_can_lookup(nd->path.dentry)) { 2048bd92d7feSAl Viro path_put(&nd->path); 2049bd23a539SAl Viro err = -ENOTDIR; 2050bd92d7feSAl Viro } 2051bd92d7feSAl Viro } 205216c2cd71SAl Viro 2053893b7775SAl Viro path_cleanup(nd); 2054bd92d7feSAl Viro return err; 205531e6b01fSNick Piggin } 205631e6b01fSNick Piggin 2057873f1eedSJeff Layton static int filename_lookup(int dfd, struct filename *name, 2058873f1eedSJeff Layton unsigned int flags, struct nameidata *nd) 2059873f1eedSJeff Layton { 20605eb6b495SAl Viro int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd); 2061873f1eedSJeff Layton if (unlikely(retval == -ECHILD)) 20625eb6b495SAl Viro retval = path_lookupat(dfd, name, flags, nd); 2063873f1eedSJeff Layton if (unlikely(retval == -ESTALE)) 20645eb6b495SAl Viro retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd); 2065873f1eedSJeff Layton 2066873f1eedSJeff Layton if (likely(!retval)) 2067adb5c247SJeff Layton audit_inode(name, nd->path.dentry, flags & LOOKUP_PARENT); 2068873f1eedSJeff Layton return retval; 2069873f1eedSJeff Layton } 2070873f1eedSJeff Layton 207179714f72SAl Viro /* does lookup, returns the object with parent locked */ 207279714f72SAl Viro struct dentry *kern_path_locked(const char *name, struct path *path) 20735590ff0dSUlrich Drepper { 207451689104SPaul Moore struct filename *filename = getname_kernel(name); 207579714f72SAl Viro struct nameidata nd; 207679714f72SAl Viro struct dentry *d; 207751689104SPaul Moore int err; 207851689104SPaul Moore 207951689104SPaul Moore if (IS_ERR(filename)) 208051689104SPaul Moore return ERR_CAST(filename); 208151689104SPaul Moore 208251689104SPaul Moore err = filename_lookup(AT_FDCWD, filename, LOOKUP_PARENT, &nd); 208351689104SPaul Moore if (err) { 208451689104SPaul Moore d = ERR_PTR(err); 208551689104SPaul Moore goto out; 208651689104SPaul Moore } 208779714f72SAl Viro if (nd.last_type != LAST_NORM) { 208879714f72SAl Viro path_put(&nd.path); 208951689104SPaul Moore d = ERR_PTR(-EINVAL); 209051689104SPaul Moore goto out; 209179714f72SAl Viro } 209279714f72SAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 20931e0ea001SAl Viro d = __lookup_hash(&nd.last, nd.path.dentry, 0); 209479714f72SAl Viro if (IS_ERR(d)) { 209579714f72SAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 209679714f72SAl Viro path_put(&nd.path); 209751689104SPaul Moore goto out; 209879714f72SAl Viro } 209979714f72SAl Viro *path = nd.path; 210051689104SPaul Moore out: 210151689104SPaul Moore putname(filename); 210279714f72SAl Viro return d; 21035590ff0dSUlrich Drepper } 21045590ff0dSUlrich Drepper 2105d1811465SAl Viro int kern_path(const char *name, unsigned int flags, struct path *path) 2106d1811465SAl Viro { 2107d1811465SAl Viro struct nameidata nd; 210874eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 210974eb8cc5SAl Viro int res = PTR_ERR(filename); 211074eb8cc5SAl Viro 211174eb8cc5SAl Viro if (!IS_ERR(filename)) { 211274eb8cc5SAl Viro res = filename_lookup(AT_FDCWD, filename, flags, &nd); 211374eb8cc5SAl Viro putname(filename); 2114d1811465SAl Viro if (!res) 2115d1811465SAl Viro *path = nd.path; 211674eb8cc5SAl Viro } 2117d1811465SAl Viro return res; 2118d1811465SAl Viro } 21194d359507SAl Viro EXPORT_SYMBOL(kern_path); 2120d1811465SAl Viro 212116f18200SJosef 'Jeff' Sipek /** 212216f18200SJosef 'Jeff' Sipek * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair 212316f18200SJosef 'Jeff' Sipek * @dentry: pointer to dentry of the base directory 212416f18200SJosef 'Jeff' Sipek * @mnt: pointer to vfs mount of the base directory 212516f18200SJosef 'Jeff' Sipek * @name: pointer to file name 212616f18200SJosef 'Jeff' Sipek * @flags: lookup flags 2127e0a01249SAl Viro * @path: pointer to struct path to fill 212816f18200SJosef 'Jeff' Sipek */ 212916f18200SJosef 'Jeff' Sipek int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt, 213016f18200SJosef 'Jeff' Sipek const char *name, unsigned int flags, 2131e0a01249SAl Viro struct path *path) 213216f18200SJosef 'Jeff' Sipek { 213374eb8cc5SAl Viro struct filename *filename = getname_kernel(name); 213474eb8cc5SAl Viro int err = PTR_ERR(filename); 213574eb8cc5SAl Viro 213674eb8cc5SAl Viro BUG_ON(flags & LOOKUP_PARENT); 213774eb8cc5SAl Viro 213874eb8cc5SAl Viro /* the first argument of filename_lookup() is ignored with LOOKUP_ROOT */ 213974eb8cc5SAl Viro if (!IS_ERR(filename)) { 2140e0a01249SAl Viro struct nameidata nd; 2141e0a01249SAl Viro nd.root.dentry = dentry; 2142e0a01249SAl Viro nd.root.mnt = mnt; 214374eb8cc5SAl Viro err = filename_lookup(AT_FDCWD, filename, 214474eb8cc5SAl Viro flags | LOOKUP_ROOT, &nd); 2145e0a01249SAl Viro if (!err) 2146e0a01249SAl Viro *path = nd.path; 214774eb8cc5SAl Viro putname(filename); 214874eb8cc5SAl Viro } 2149e0a01249SAl Viro return err; 215016f18200SJosef 'Jeff' Sipek } 21514d359507SAl Viro EXPORT_SYMBOL(vfs_path_lookup); 215216f18200SJosef 'Jeff' Sipek 2153eead1911SChristoph Hellwig /** 2154a6b91919SRandy Dunlap * lookup_one_len - filesystem helper to lookup single pathname component 2155eead1911SChristoph Hellwig * @name: pathname component to lookup 2156eead1911SChristoph Hellwig * @base: base directory to lookup from 2157eead1911SChristoph Hellwig * @len: maximum length @len should be interpreted to 2158eead1911SChristoph Hellwig * 2159a6b91919SRandy Dunlap * Note that this routine is purely a helper for filesystem usage and should 21609e7543e9SAl Viro * not be called by generic code. 2161eead1911SChristoph Hellwig */ 2162057f6c01SJames Morris struct dentry *lookup_one_len(const char *name, struct dentry *base, int len) 2163057f6c01SJames Morris { 2164057f6c01SJames Morris struct qstr this; 21656a96ba54SAl Viro unsigned int c; 2166cda309deSMiklos Szeredi int err; 2167057f6c01SJames Morris 21682f9092e1SDavid Woodhouse WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex)); 21692f9092e1SDavid Woodhouse 21706a96ba54SAl Viro this.name = name; 21716a96ba54SAl Viro this.len = len; 21720145acc2SLinus Torvalds this.hash = full_name_hash(name, len); 21736a96ba54SAl Viro if (!len) 21746a96ba54SAl Viro return ERR_PTR(-EACCES); 21756a96ba54SAl Viro 217621d8a15aSAl Viro if (unlikely(name[0] == '.')) { 217721d8a15aSAl Viro if (len < 2 || (len == 2 && name[1] == '.')) 217821d8a15aSAl Viro return ERR_PTR(-EACCES); 217921d8a15aSAl Viro } 218021d8a15aSAl Viro 21816a96ba54SAl Viro while (len--) { 21826a96ba54SAl Viro c = *(const unsigned char *)name++; 21836a96ba54SAl Viro if (c == '/' || c == '\0') 21846a96ba54SAl Viro return ERR_PTR(-EACCES); 21856a96ba54SAl Viro } 21865a202bcdSAl Viro /* 21875a202bcdSAl Viro * See if the low-level filesystem might want 21885a202bcdSAl Viro * to use its own hash.. 21895a202bcdSAl Viro */ 21905a202bcdSAl Viro if (base->d_flags & DCACHE_OP_HASH) { 2191da53be12SLinus Torvalds int err = base->d_op->d_hash(base, &this); 21925a202bcdSAl Viro if (err < 0) 21935a202bcdSAl Viro return ERR_PTR(err); 21945a202bcdSAl Viro } 2195eead1911SChristoph Hellwig 2196cda309deSMiklos Szeredi err = inode_permission(base->d_inode, MAY_EXEC); 2197cda309deSMiklos Szeredi if (err) 2198cda309deSMiklos Szeredi return ERR_PTR(err); 2199cda309deSMiklos Szeredi 220072bd866aSAl Viro return __lookup_hash(&this, base, 0); 2201057f6c01SJames Morris } 22024d359507SAl Viro EXPORT_SYMBOL(lookup_one_len); 2203057f6c01SJames Morris 22041fa1e7f6SAndy Whitcroft int user_path_at_empty(int dfd, const char __user *name, unsigned flags, 22051fa1e7f6SAndy Whitcroft struct path *path, int *empty) 22061da177e4SLinus Torvalds { 22072d8f3038SAl Viro struct nameidata nd; 220891a27b2aSJeff Layton struct filename *tmp = getname_flags(name, flags, empty); 22091da177e4SLinus Torvalds int err = PTR_ERR(tmp); 22101da177e4SLinus Torvalds if (!IS_ERR(tmp)) { 22112d8f3038SAl Viro 22122d8f3038SAl Viro BUG_ON(flags & LOOKUP_PARENT); 22132d8f3038SAl Viro 2214873f1eedSJeff Layton err = filename_lookup(dfd, tmp, flags, &nd); 22151da177e4SLinus Torvalds putname(tmp); 22162d8f3038SAl Viro if (!err) 22172d8f3038SAl Viro *path = nd.path; 22181da177e4SLinus Torvalds } 22191da177e4SLinus Torvalds return err; 22201da177e4SLinus Torvalds } 22211da177e4SLinus Torvalds 22221fa1e7f6SAndy Whitcroft int user_path_at(int dfd, const char __user *name, unsigned flags, 22231fa1e7f6SAndy Whitcroft struct path *path) 22241fa1e7f6SAndy Whitcroft { 2225f7493e5dSLinus Torvalds return user_path_at_empty(dfd, name, flags, path, NULL); 22261fa1e7f6SAndy Whitcroft } 22274d359507SAl Viro EXPORT_SYMBOL(user_path_at); 22281fa1e7f6SAndy Whitcroft 2229873f1eedSJeff Layton /* 2230873f1eedSJeff Layton * NB: most callers don't do anything directly with the reference to the 2231873f1eedSJeff Layton * to struct filename, but the nd->last pointer points into the name string 2232873f1eedSJeff Layton * allocated by getname. So we must hold the reference to it until all 2233873f1eedSJeff Layton * path-walking is complete. 2234873f1eedSJeff Layton */ 223591a27b2aSJeff Layton static struct filename * 2236f5beed75SAl Viro user_path_parent(int dfd, const char __user *path, 2237f5beed75SAl Viro struct path *parent, 2238f5beed75SAl Viro struct qstr *last, 2239f5beed75SAl Viro int *type, 22409e790bd6SJeff Layton unsigned int flags) 22412ad94ae6SAl Viro { 2242f5beed75SAl Viro struct nameidata nd; 224391a27b2aSJeff Layton struct filename *s = getname(path); 22442ad94ae6SAl Viro int error; 22452ad94ae6SAl Viro 22469e790bd6SJeff Layton /* only LOOKUP_REVAL is allowed in extra flags */ 22479e790bd6SJeff Layton flags &= LOOKUP_REVAL; 22489e790bd6SJeff Layton 22492ad94ae6SAl Viro if (IS_ERR(s)) 225091a27b2aSJeff Layton return s; 22512ad94ae6SAl Viro 2252f5beed75SAl Viro error = filename_lookup(dfd, s, flags | LOOKUP_PARENT, &nd); 225391a27b2aSJeff Layton if (error) { 22542ad94ae6SAl Viro putname(s); 225591a27b2aSJeff Layton return ERR_PTR(error); 225691a27b2aSJeff Layton } 2257f5beed75SAl Viro *parent = nd.path; 2258f5beed75SAl Viro *last = nd.last; 2259f5beed75SAl Viro *type = nd.last_type; 22602ad94ae6SAl Viro 226191a27b2aSJeff Layton return s; 22622ad94ae6SAl Viro } 22632ad94ae6SAl Viro 22648033426eSJeff Layton /** 2265197df04cSAl Viro * mountpoint_last - look up last component for umount 22668033426eSJeff Layton * @nd: pathwalk nameidata - currently pointing at parent directory of "last" 22678033426eSJeff Layton * @path: pointer to container for result 22688033426eSJeff Layton * 22698033426eSJeff Layton * This is a special lookup_last function just for umount. In this case, we 22708033426eSJeff Layton * need to resolve the path without doing any revalidation. 22718033426eSJeff Layton * 22728033426eSJeff Layton * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since 22738033426eSJeff Layton * mountpoints are always pinned in the dcache, their ancestors are too. Thus, 22748033426eSJeff Layton * in almost all cases, this lookup will be served out of the dcache. The only 22758033426eSJeff Layton * cases where it won't are if nd->last refers to a symlink or the path is 22768033426eSJeff Layton * bogus and it doesn't exist. 22778033426eSJeff Layton * 22788033426eSJeff Layton * Returns: 22798033426eSJeff Layton * -error: if there was an error during lookup. This includes -ENOENT if the 22808033426eSJeff Layton * lookup found a negative dentry. The nd->path reference will also be 22818033426eSJeff Layton * put in this case. 22828033426eSJeff Layton * 22838033426eSJeff Layton * 0: if we successfully resolved nd->path and found it to not to be a 22848033426eSJeff Layton * symlink that needs to be followed. "path" will also be populated. 22858033426eSJeff Layton * The nd->path reference will also be put. 22868033426eSJeff Layton * 22878033426eSJeff Layton * 1: if we successfully resolved nd->last and found it to be a symlink 22888033426eSJeff Layton * that needs to be followed. "path" will be populated with the path 22898033426eSJeff Layton * to the link, and nd->path will *not* be put. 22908033426eSJeff Layton */ 22918033426eSJeff Layton static int 2292197df04cSAl Viro mountpoint_last(struct nameidata *nd, struct path *path) 22938033426eSJeff Layton { 22948033426eSJeff Layton int error = 0; 22958033426eSJeff Layton struct dentry *dentry; 22968033426eSJeff Layton struct dentry *dir = nd->path.dentry; 22978033426eSJeff Layton 229835759521SAl Viro /* If we're in rcuwalk, drop out of it to handle last component */ 229935759521SAl Viro if (nd->flags & LOOKUP_RCU) { 230035759521SAl Viro if (unlazy_walk(nd, NULL)) { 23018033426eSJeff Layton error = -ECHILD; 230235759521SAl Viro goto out; 230335759521SAl Viro } 23048033426eSJeff Layton } 23058033426eSJeff Layton 23068033426eSJeff Layton nd->flags &= ~LOOKUP_PARENT; 23078033426eSJeff Layton 23088033426eSJeff Layton if (unlikely(nd->last_type != LAST_NORM)) { 23098033426eSJeff Layton error = handle_dots(nd, nd->last_type); 231035759521SAl Viro if (error) 231135759521SAl Viro goto out; 23128033426eSJeff Layton dentry = dget(nd->path.dentry); 231335759521SAl Viro goto done; 23148033426eSJeff Layton } 23158033426eSJeff Layton 23168033426eSJeff Layton mutex_lock(&dir->d_inode->i_mutex); 23178033426eSJeff Layton dentry = d_lookup(dir, &nd->last); 23188033426eSJeff Layton if (!dentry) { 23198033426eSJeff Layton /* 23208033426eSJeff Layton * No cached dentry. Mounted dentries are pinned in the cache, 23218033426eSJeff Layton * so that means that this dentry is probably a symlink or the 23228033426eSJeff Layton * path doesn't actually point to a mounted dentry. 23238033426eSJeff Layton */ 23248033426eSJeff Layton dentry = d_alloc(dir, &nd->last); 23258033426eSJeff Layton if (!dentry) { 23268033426eSJeff Layton error = -ENOMEM; 2327bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 232835759521SAl Viro goto out; 23298033426eSJeff Layton } 233035759521SAl Viro dentry = lookup_real(dir->d_inode, dentry, nd->flags); 233135759521SAl Viro error = PTR_ERR(dentry); 2332bcceeebaSDave Jones if (IS_ERR(dentry)) { 2333bcceeebaSDave Jones mutex_unlock(&dir->d_inode->i_mutex); 233435759521SAl Viro goto out; 23358033426eSJeff Layton } 2336bcceeebaSDave Jones } 23378033426eSJeff Layton mutex_unlock(&dir->d_inode->i_mutex); 23388033426eSJeff Layton 233935759521SAl Viro done: 2340698934dfSDavid Howells if (d_is_negative(dentry)) { 23418033426eSJeff Layton error = -ENOENT; 23428033426eSJeff Layton dput(dentry); 234335759521SAl Viro goto out; 234435759521SAl Viro } 23458033426eSJeff Layton path->dentry = dentry; 2346295dc39dSVasily Averin path->mnt = nd->path.mnt; 2347caa85634SAl Viro if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW)) { 2348caa85634SAl Viro nd->link = *path; 23498033426eSJeff Layton return 1; 2350caa85634SAl Viro } 2351295dc39dSVasily Averin mntget(path->mnt); 23528033426eSJeff Layton follow_mount(path); 235335759521SAl Viro error = 0; 235435759521SAl Viro out: 23558033426eSJeff Layton terminate_walk(nd); 23568033426eSJeff Layton return error; 23578033426eSJeff Layton } 23588033426eSJeff Layton 23598033426eSJeff Layton /** 2360197df04cSAl Viro * path_mountpoint - look up a path to be umounted 23618033426eSJeff Layton * @dfd: directory file descriptor to start walk from 23628033426eSJeff Layton * @name: full pathname to walk 2363606d6fe3SRandy Dunlap * @path: pointer to container for result 23648033426eSJeff Layton * @flags: lookup flags 23658033426eSJeff Layton * 23668033426eSJeff Layton * Look up the given name, but don't attempt to revalidate the last component. 2367606d6fe3SRandy Dunlap * Returns 0 and "path" will be valid on success; Returns error otherwise. 23688033426eSJeff Layton */ 23698033426eSJeff Layton static int 2370668696dcSAl Viro path_mountpoint(int dfd, const struct filename *name, struct path *path, 237146afd6f6SAl Viro struct nameidata *nd, unsigned int flags) 23728033426eSJeff Layton { 237346afd6f6SAl Viro int err = path_init(dfd, name, flags, nd); 23748033426eSJeff Layton if (unlikely(err)) 2375115cbfdcSAl Viro goto out; 23768033426eSJeff Layton 237746afd6f6SAl Viro err = mountpoint_last(nd, path); 23788033426eSJeff Layton while (err > 0) { 23798033426eSJeff Layton void *cookie; 23808033426eSJeff Layton struct path link = *path; 238195fa25d9SAl Viro err = trailing_symlink(&link, nd, &cookie); 23828033426eSJeff Layton if (err) 23838033426eSJeff Layton break; 238446afd6f6SAl Viro err = mountpoint_last(nd, path); 238546afd6f6SAl Viro put_link(nd, &link, cookie); 23868033426eSJeff Layton } 23878033426eSJeff Layton out: 238846afd6f6SAl Viro path_cleanup(nd); 23898033426eSJeff Layton return err; 23908033426eSJeff Layton } 23918033426eSJeff Layton 23922d864651SAl Viro static int 2393668696dcSAl Viro filename_mountpoint(int dfd, struct filename *name, struct path *path, 23942d864651SAl Viro unsigned int flags) 23952d864651SAl Viro { 239646afd6f6SAl Viro struct nameidata nd; 2397cbaab2dbSAl Viro int error; 2398668696dcSAl Viro if (IS_ERR(name)) 2399668696dcSAl Viro return PTR_ERR(name); 240046afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_RCU); 24012d864651SAl Viro if (unlikely(error == -ECHILD)) 240246afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags); 24032d864651SAl Viro if (unlikely(error == -ESTALE)) 240446afd6f6SAl Viro error = path_mountpoint(dfd, name, path, &nd, flags | LOOKUP_REVAL); 24052d864651SAl Viro if (likely(!error)) 2406668696dcSAl Viro audit_inode(name, path->dentry, 0); 2407668696dcSAl Viro putname(name); 24082d864651SAl Viro return error; 24092d864651SAl Viro } 24102d864651SAl Viro 24118033426eSJeff Layton /** 2412197df04cSAl Viro * user_path_mountpoint_at - lookup a path from userland in order to umount it 24138033426eSJeff Layton * @dfd: directory file descriptor 24148033426eSJeff Layton * @name: pathname from userland 24158033426eSJeff Layton * @flags: lookup flags 24168033426eSJeff Layton * @path: pointer to container to hold result 24178033426eSJeff Layton * 24188033426eSJeff Layton * A umount is a special case for path walking. We're not actually interested 24198033426eSJeff Layton * in the inode in this situation, and ESTALE errors can be a problem. We 24208033426eSJeff Layton * simply want track down the dentry and vfsmount attached at the mountpoint 24218033426eSJeff Layton * and avoid revalidating the last component. 24228033426eSJeff Layton * 24238033426eSJeff Layton * Returns 0 and populates "path" on success. 24248033426eSJeff Layton */ 24258033426eSJeff Layton int 2426197df04cSAl Viro user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags, 24278033426eSJeff Layton struct path *path) 24288033426eSJeff Layton { 2429cbaab2dbSAl Viro return filename_mountpoint(dfd, getname(name), path, flags); 24308033426eSJeff Layton } 24318033426eSJeff Layton 24322d864651SAl Viro int 24332d864651SAl Viro kern_path_mountpoint(int dfd, const char *name, struct path *path, 24342d864651SAl Viro unsigned int flags) 24352d864651SAl Viro { 2436cbaab2dbSAl Viro return filename_mountpoint(dfd, getname_kernel(name), path, flags); 24372d864651SAl Viro } 24382d864651SAl Viro EXPORT_SYMBOL(kern_path_mountpoint); 24392d864651SAl Viro 2440cbdf35bcSMiklos Szeredi int __check_sticky(struct inode *dir, struct inode *inode) 24411da177e4SLinus Torvalds { 24428e96e3b7SEric W. Biederman kuid_t fsuid = current_fsuid(); 2443da9592edSDavid Howells 24448e96e3b7SEric W. Biederman if (uid_eq(inode->i_uid, fsuid)) 24451da177e4SLinus Torvalds return 0; 24468e96e3b7SEric W. Biederman if (uid_eq(dir->i_uid, fsuid)) 24471da177e4SLinus Torvalds return 0; 244823adbe12SAndy Lutomirski return !capable_wrt_inode_uidgid(inode, CAP_FOWNER); 24491da177e4SLinus Torvalds } 2450cbdf35bcSMiklos Szeredi EXPORT_SYMBOL(__check_sticky); 24511da177e4SLinus Torvalds 24521da177e4SLinus Torvalds /* 24531da177e4SLinus Torvalds * Check whether we can remove a link victim from directory dir, check 24541da177e4SLinus Torvalds * whether the type of victim is right. 24551da177e4SLinus Torvalds * 1. We can't do it if dir is read-only (done in permission()) 24561da177e4SLinus Torvalds * 2. We should have write and exec permissions on dir 24571da177e4SLinus Torvalds * 3. We can't remove anything from append-only dir 24581da177e4SLinus Torvalds * 4. We can't do anything with immutable dir (done in permission()) 24591da177e4SLinus Torvalds * 5. If the sticky bit on dir is set we should either 24601da177e4SLinus Torvalds * a. be owner of dir, or 24611da177e4SLinus Torvalds * b. be owner of victim, or 24621da177e4SLinus Torvalds * c. have CAP_FOWNER capability 24631da177e4SLinus Torvalds * 6. If the victim is append-only or immutable we can't do antyhing with 24641da177e4SLinus Torvalds * links pointing to it. 24651da177e4SLinus Torvalds * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR. 24661da177e4SLinus Torvalds * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR. 24671da177e4SLinus Torvalds * 9. We can't remove a root or mountpoint. 24681da177e4SLinus Torvalds * 10. We don't allow removal of NFS sillyrenamed files; it's handled by 24691da177e4SLinus Torvalds * nfs_async_unlink(). 24701da177e4SLinus Torvalds */ 2471b18825a7SDavid Howells static int may_delete(struct inode *dir, struct dentry *victim, bool isdir) 24721da177e4SLinus Torvalds { 2473b18825a7SDavid Howells struct inode *inode = victim->d_inode; 24741da177e4SLinus Torvalds int error; 24751da177e4SLinus Torvalds 2476b18825a7SDavid Howells if (d_is_negative(victim)) 24771da177e4SLinus Torvalds return -ENOENT; 2478b18825a7SDavid Howells BUG_ON(!inode); 24791da177e4SLinus Torvalds 24801da177e4SLinus Torvalds BUG_ON(victim->d_parent->d_inode != dir); 24814fa6b5ecSJeff Layton audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE); 24821da177e4SLinus Torvalds 2483f419a2e3SAl Viro error = inode_permission(dir, MAY_WRITE | MAY_EXEC); 24841da177e4SLinus Torvalds if (error) 24851da177e4SLinus Torvalds return error; 24861da177e4SLinus Torvalds if (IS_APPEND(dir)) 24871da177e4SLinus Torvalds return -EPERM; 2488b18825a7SDavid Howells 2489b18825a7SDavid Howells if (check_sticky(dir, inode) || IS_APPEND(inode) || 2490b18825a7SDavid Howells IS_IMMUTABLE(inode) || IS_SWAPFILE(inode)) 24911da177e4SLinus Torvalds return -EPERM; 24921da177e4SLinus Torvalds if (isdir) { 249344b1d530SMiklos Szeredi if (!d_is_dir(victim)) 24941da177e4SLinus Torvalds return -ENOTDIR; 24951da177e4SLinus Torvalds if (IS_ROOT(victim)) 24961da177e4SLinus Torvalds return -EBUSY; 249744b1d530SMiklos Szeredi } else if (d_is_dir(victim)) 24981da177e4SLinus Torvalds return -EISDIR; 24991da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25001da177e4SLinus Torvalds return -ENOENT; 25011da177e4SLinus Torvalds if (victim->d_flags & DCACHE_NFSFS_RENAMED) 25021da177e4SLinus Torvalds return -EBUSY; 25031da177e4SLinus Torvalds return 0; 25041da177e4SLinus Torvalds } 25051da177e4SLinus Torvalds 25061da177e4SLinus Torvalds /* Check whether we can create an object with dentry child in directory 25071da177e4SLinus Torvalds * dir. 25081da177e4SLinus Torvalds * 1. We can't do it if child already exists (open has special treatment for 25091da177e4SLinus Torvalds * this case, but since we are inlined it's OK) 25101da177e4SLinus Torvalds * 2. We can't do it if dir is read-only (done in permission()) 25111da177e4SLinus Torvalds * 3. We should have write and exec permissions on dir 25121da177e4SLinus Torvalds * 4. We can't do it if dir is immutable (done in permission()) 25131da177e4SLinus Torvalds */ 2514a95164d9SMiklos Szeredi static inline int may_create(struct inode *dir, struct dentry *child) 25151da177e4SLinus Torvalds { 251614e972b4SJeff Layton audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE); 25171da177e4SLinus Torvalds if (child->d_inode) 25181da177e4SLinus Torvalds return -EEXIST; 25191da177e4SLinus Torvalds if (IS_DEADDIR(dir)) 25201da177e4SLinus Torvalds return -ENOENT; 2521f419a2e3SAl Viro return inode_permission(dir, MAY_WRITE | MAY_EXEC); 25221da177e4SLinus Torvalds } 25231da177e4SLinus Torvalds 25241da177e4SLinus Torvalds /* 25251da177e4SLinus Torvalds * p1 and p2 should be directories on the same fs. 25261da177e4SLinus Torvalds */ 25271da177e4SLinus Torvalds struct dentry *lock_rename(struct dentry *p1, struct dentry *p2) 25281da177e4SLinus Torvalds { 25291da177e4SLinus Torvalds struct dentry *p; 25301da177e4SLinus Torvalds 25311da177e4SLinus Torvalds if (p1 == p2) { 2532f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 25331da177e4SLinus Torvalds return NULL; 25341da177e4SLinus Torvalds } 25351da177e4SLinus Torvalds 2536a11f3a05SArjan van de Ven mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25371da177e4SLinus Torvalds 2538e2761a11SOGAWA Hirofumi p = d_ancestor(p2, p1); 2539e2761a11SOGAWA Hirofumi if (p) { 2540f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT); 2541f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD); 25421da177e4SLinus Torvalds return p; 25431da177e4SLinus Torvalds } 25441da177e4SLinus Torvalds 2545e2761a11SOGAWA Hirofumi p = d_ancestor(p1, p2); 2546e2761a11SOGAWA Hirofumi if (p) { 2547f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2548f2eace23SIngo Molnar mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD); 25491da177e4SLinus Torvalds return p; 25501da177e4SLinus Torvalds } 25511da177e4SLinus Torvalds 2552f2eace23SIngo Molnar mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT); 2553d1b72cc6SMiklos Szeredi mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT2); 25541da177e4SLinus Torvalds return NULL; 25551da177e4SLinus Torvalds } 25564d359507SAl Viro EXPORT_SYMBOL(lock_rename); 25571da177e4SLinus Torvalds 25581da177e4SLinus Torvalds void unlock_rename(struct dentry *p1, struct dentry *p2) 25591da177e4SLinus Torvalds { 25601b1dcc1bSJes Sorensen mutex_unlock(&p1->d_inode->i_mutex); 25611da177e4SLinus Torvalds if (p1 != p2) { 25621b1dcc1bSJes Sorensen mutex_unlock(&p2->d_inode->i_mutex); 2563a11f3a05SArjan van de Ven mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex); 25641da177e4SLinus Torvalds } 25651da177e4SLinus Torvalds } 25664d359507SAl Viro EXPORT_SYMBOL(unlock_rename); 25671da177e4SLinus Torvalds 25684acdaf27SAl Viro int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 2569312b63fbSAl Viro bool want_excl) 25701da177e4SLinus Torvalds { 2571a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 25721da177e4SLinus Torvalds if (error) 25731da177e4SLinus Torvalds return error; 25741da177e4SLinus Torvalds 2575acfa4380SAl Viro if (!dir->i_op->create) 25761da177e4SLinus Torvalds return -EACCES; /* shouldn't it be ENOSYS? */ 25771da177e4SLinus Torvalds mode &= S_IALLUGO; 25781da177e4SLinus Torvalds mode |= S_IFREG; 25791da177e4SLinus Torvalds error = security_inode_create(dir, dentry, mode); 25801da177e4SLinus Torvalds if (error) 25811da177e4SLinus Torvalds return error; 2582312b63fbSAl Viro error = dir->i_op->create(dir, dentry, mode, want_excl); 2583a74574aaSStephen Smalley if (!error) 2584f38aa942SAmy Griffis fsnotify_create(dir, dentry); 25851da177e4SLinus Torvalds return error; 25861da177e4SLinus Torvalds } 25874d359507SAl Viro EXPORT_SYMBOL(vfs_create); 25881da177e4SLinus Torvalds 258973d049a4SAl Viro static int may_open(struct path *path, int acc_mode, int flag) 25901da177e4SLinus Torvalds { 25913fb64190SChristoph Hellwig struct dentry *dentry = path->dentry; 25921da177e4SLinus Torvalds struct inode *inode = dentry->d_inode; 25931da177e4SLinus Torvalds int error; 25941da177e4SLinus Torvalds 2595bcda7652SAl Viro /* O_PATH? */ 2596bcda7652SAl Viro if (!acc_mode) 2597bcda7652SAl Viro return 0; 2598bcda7652SAl Viro 25991da177e4SLinus Torvalds if (!inode) 26001da177e4SLinus Torvalds return -ENOENT; 26011da177e4SLinus Torvalds 2602c8fe8f30SChristoph Hellwig switch (inode->i_mode & S_IFMT) { 2603c8fe8f30SChristoph Hellwig case S_IFLNK: 26041da177e4SLinus Torvalds return -ELOOP; 2605c8fe8f30SChristoph Hellwig case S_IFDIR: 2606c8fe8f30SChristoph Hellwig if (acc_mode & MAY_WRITE) 26071da177e4SLinus Torvalds return -EISDIR; 2608c8fe8f30SChristoph Hellwig break; 2609c8fe8f30SChristoph Hellwig case S_IFBLK: 2610c8fe8f30SChristoph Hellwig case S_IFCHR: 26113fb64190SChristoph Hellwig if (path->mnt->mnt_flags & MNT_NODEV) 26121da177e4SLinus Torvalds return -EACCES; 2613c8fe8f30SChristoph Hellwig /*FALLTHRU*/ 2614c8fe8f30SChristoph Hellwig case S_IFIFO: 2615c8fe8f30SChristoph Hellwig case S_IFSOCK: 26161da177e4SLinus Torvalds flag &= ~O_TRUNC; 2617c8fe8f30SChristoph Hellwig break; 26184a3fd211SDave Hansen } 2619b41572e9SDave Hansen 26203fb64190SChristoph Hellwig error = inode_permission(inode, acc_mode); 2621b41572e9SDave Hansen if (error) 2622b41572e9SDave Hansen return error; 26236146f0d5SMimi Zohar 26241da177e4SLinus Torvalds /* 26251da177e4SLinus Torvalds * An append-only file must be opened in append mode for writing. 26261da177e4SLinus Torvalds */ 26271da177e4SLinus Torvalds if (IS_APPEND(inode)) { 26288737c930SAl Viro if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND)) 26297715b521SAl Viro return -EPERM; 26301da177e4SLinus Torvalds if (flag & O_TRUNC) 26317715b521SAl Viro return -EPERM; 26321da177e4SLinus Torvalds } 26331da177e4SLinus Torvalds 26341da177e4SLinus Torvalds /* O_NOATIME can only be set by the owner or superuser */ 26352e149670SSerge E. Hallyn if (flag & O_NOATIME && !inode_owner_or_capable(inode)) 26367715b521SAl Viro return -EPERM; 26371da177e4SLinus Torvalds 2638f3c7691eSJ. Bruce Fields return 0; 26397715b521SAl Viro } 26407715b521SAl Viro 2641e1181ee6SJeff Layton static int handle_truncate(struct file *filp) 26427715b521SAl Viro { 2643e1181ee6SJeff Layton struct path *path = &filp->f_path; 26447715b521SAl Viro struct inode *inode = path->dentry->d_inode; 26457715b521SAl Viro int error = get_write_access(inode); 26461da177e4SLinus Torvalds if (error) 26477715b521SAl Viro return error; 26481da177e4SLinus Torvalds /* 26491da177e4SLinus Torvalds * Refuse to truncate files with mandatory locks held on them. 26501da177e4SLinus Torvalds */ 2651d7a06983SJeff Layton error = locks_verify_locked(filp); 2652be6d3e56SKentaro Takeda if (!error) 2653ea0d3ab2STetsuo Handa error = security_path_truncate(path); 26541da177e4SLinus Torvalds if (!error) { 26557715b521SAl Viro error = do_truncate(path->dentry, 0, 2656d139d7ffSMiklos Szeredi ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, 2657e1181ee6SJeff Layton filp); 26581da177e4SLinus Torvalds } 26591da177e4SLinus Torvalds put_write_access(inode); 2660acd0c935SMimi Zohar return error; 26611da177e4SLinus Torvalds } 26621da177e4SLinus Torvalds 2663d57999e1SDave Hansen static inline int open_to_namei_flags(int flag) 2664d57999e1SDave Hansen { 26658a5e929dSAl Viro if ((flag & O_ACCMODE) == 3) 26668a5e929dSAl Viro flag--; 2667d57999e1SDave Hansen return flag; 2668d57999e1SDave Hansen } 2669d57999e1SDave Hansen 2670d18e9008SMiklos Szeredi static int may_o_create(struct path *dir, struct dentry *dentry, umode_t mode) 2671d18e9008SMiklos Szeredi { 2672d18e9008SMiklos Szeredi int error = security_path_mknod(dir, dentry, mode, 0); 2673d18e9008SMiklos Szeredi if (error) 2674d18e9008SMiklos Szeredi return error; 2675d18e9008SMiklos Szeredi 2676d18e9008SMiklos Szeredi error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC); 2677d18e9008SMiklos Szeredi if (error) 2678d18e9008SMiklos Szeredi return error; 2679d18e9008SMiklos Szeredi 2680d18e9008SMiklos Szeredi return security_inode_create(dir->dentry->d_inode, dentry, mode); 2681d18e9008SMiklos Szeredi } 2682d18e9008SMiklos Szeredi 26831acf0af9SDavid Howells /* 26841acf0af9SDavid Howells * Attempt to atomically look up, create and open a file from a negative 26851acf0af9SDavid Howells * dentry. 26861acf0af9SDavid Howells * 26871acf0af9SDavid Howells * Returns 0 if successful. The file will have been created and attached to 26881acf0af9SDavid Howells * @file by the filesystem calling finish_open(). 26891acf0af9SDavid Howells * 26901acf0af9SDavid Howells * Returns 1 if the file was looked up only or didn't need creating. The 26911acf0af9SDavid Howells * caller will need to perform the open themselves. @path will have been 26921acf0af9SDavid Howells * updated to point to the new dentry. This may be negative. 26931acf0af9SDavid Howells * 26941acf0af9SDavid Howells * Returns an error code otherwise. 26951acf0af9SDavid Howells */ 26962675a4ebSAl Viro static int atomic_open(struct nameidata *nd, struct dentry *dentry, 269730d90494SAl Viro struct path *path, struct file *file, 2698015c3bbcSMiklos Szeredi const struct open_flags *op, 269964894cf8SAl Viro bool got_write, bool need_lookup, 270047237687SAl Viro int *opened) 2701d18e9008SMiklos Szeredi { 2702d18e9008SMiklos Szeredi struct inode *dir = nd->path.dentry->d_inode; 2703d18e9008SMiklos Szeredi unsigned open_flag = open_to_namei_flags(op->open_flag); 2704d18e9008SMiklos Szeredi umode_t mode; 2705d18e9008SMiklos Szeredi int error; 2706d18e9008SMiklos Szeredi int acc_mode; 2707d18e9008SMiklos Szeredi int create_error = 0; 2708d18e9008SMiklos Szeredi struct dentry *const DENTRY_NOT_SET = (void *) -1UL; 2709116cc022SMiklos Szeredi bool excl; 2710d18e9008SMiklos Szeredi 2711d18e9008SMiklos Szeredi BUG_ON(dentry->d_inode); 2712d18e9008SMiklos Szeredi 2713d18e9008SMiklos Szeredi /* Don't create child dentry for a dead directory. */ 2714d18e9008SMiklos Szeredi if (unlikely(IS_DEADDIR(dir))) { 27152675a4ebSAl Viro error = -ENOENT; 2716d18e9008SMiklos Szeredi goto out; 2717d18e9008SMiklos Szeredi } 2718d18e9008SMiklos Szeredi 271962b259d8SMiklos Szeredi mode = op->mode; 2720d18e9008SMiklos Szeredi if ((open_flag & O_CREAT) && !IS_POSIXACL(dir)) 2721d18e9008SMiklos Szeredi mode &= ~current_umask(); 2722d18e9008SMiklos Szeredi 2723116cc022SMiklos Szeredi excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT); 2724116cc022SMiklos Szeredi if (excl) 2725d18e9008SMiklos Szeredi open_flag &= ~O_TRUNC; 2726d18e9008SMiklos Szeredi 2727d18e9008SMiklos Szeredi /* 2728d18e9008SMiklos Szeredi * Checking write permission is tricky, bacuse we don't know if we are 2729d18e9008SMiklos Szeredi * going to actually need it: O_CREAT opens should work as long as the 2730d18e9008SMiklos Szeredi * file exists. But checking existence breaks atomicity. The trick is 2731d18e9008SMiklos Szeredi * to check access and if not granted clear O_CREAT from the flags. 2732d18e9008SMiklos Szeredi * 2733d18e9008SMiklos Szeredi * Another problem is returing the "right" error value (e.g. for an 2734d18e9008SMiklos Szeredi * O_EXCL open we want to return EEXIST not EROFS). 2735d18e9008SMiklos Szeredi */ 273664894cf8SAl Viro if (((open_flag & (O_CREAT | O_TRUNC)) || 273764894cf8SAl Viro (open_flag & O_ACCMODE) != O_RDONLY) && unlikely(!got_write)) { 273864894cf8SAl Viro if (!(open_flag & O_CREAT)) { 2739d18e9008SMiklos Szeredi /* 2740d18e9008SMiklos Szeredi * No O_CREATE -> atomicity not a requirement -> fall 2741d18e9008SMiklos Szeredi * back to lookup + open 2742d18e9008SMiklos Szeredi */ 2743d18e9008SMiklos Szeredi goto no_open; 2744d18e9008SMiklos Szeredi } else if (open_flag & (O_EXCL | O_TRUNC)) { 2745d18e9008SMiklos Szeredi /* Fall back and fail with the right error */ 274664894cf8SAl Viro create_error = -EROFS; 2747d18e9008SMiklos Szeredi goto no_open; 2748d18e9008SMiklos Szeredi } else { 2749d18e9008SMiklos Szeredi /* No side effects, safe to clear O_CREAT */ 275064894cf8SAl Viro create_error = -EROFS; 2751d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2752d18e9008SMiklos Szeredi } 2753d18e9008SMiklos Szeredi } 2754d18e9008SMiklos Szeredi 2755d18e9008SMiklos Szeredi if (open_flag & O_CREAT) { 275638227f78SMiklos Szeredi error = may_o_create(&nd->path, dentry, mode); 2757d18e9008SMiklos Szeredi if (error) { 2758d18e9008SMiklos Szeredi create_error = error; 2759d18e9008SMiklos Szeredi if (open_flag & O_EXCL) 2760d18e9008SMiklos Szeredi goto no_open; 2761d18e9008SMiklos Szeredi open_flag &= ~O_CREAT; 2762d18e9008SMiklos Szeredi } 2763d18e9008SMiklos Szeredi } 2764d18e9008SMiklos Szeredi 2765d18e9008SMiklos Szeredi if (nd->flags & LOOKUP_DIRECTORY) 2766d18e9008SMiklos Szeredi open_flag |= O_DIRECTORY; 2767d18e9008SMiklos Szeredi 276830d90494SAl Viro file->f_path.dentry = DENTRY_NOT_SET; 276930d90494SAl Viro file->f_path.mnt = nd->path.mnt; 277030d90494SAl Viro error = dir->i_op->atomic_open(dir, dentry, file, open_flag, mode, 277147237687SAl Viro opened); 2772d9585277SAl Viro if (error < 0) { 2773d9585277SAl Viro if (create_error && error == -ENOENT) 2774d9585277SAl Viro error = create_error; 2775d18e9008SMiklos Szeredi goto out; 2776d18e9008SMiklos Szeredi } 2777d18e9008SMiklos Szeredi 2778d9585277SAl Viro if (error) { /* returned 1, that is */ 277930d90494SAl Viro if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) { 27802675a4ebSAl Viro error = -EIO; 2781d18e9008SMiklos Szeredi goto out; 2782d18e9008SMiklos Szeredi } 278330d90494SAl Viro if (file->f_path.dentry) { 2784d18e9008SMiklos Szeredi dput(dentry); 278530d90494SAl Viro dentry = file->f_path.dentry; 2786d18e9008SMiklos Szeredi } 278703da633aSAl Viro if (*opened & FILE_CREATED) 278803da633aSAl Viro fsnotify_create(dir, dentry); 278903da633aSAl Viro if (!dentry->d_inode) { 279003da633aSAl Viro WARN_ON(*opened & FILE_CREATED); 279103da633aSAl Viro if (create_error) { 279262b2ce96SSage Weil error = create_error; 279362b2ce96SSage Weil goto out; 279462b2ce96SSage Weil } 279503da633aSAl Viro } else { 279603da633aSAl Viro if (excl && !(*opened & FILE_CREATED)) { 279703da633aSAl Viro error = -EEXIST; 279803da633aSAl Viro goto out; 279903da633aSAl Viro } 280003da633aSAl Viro } 2801d18e9008SMiklos Szeredi goto looked_up; 2802d18e9008SMiklos Szeredi } 2803d18e9008SMiklos Szeredi 2804d18e9008SMiklos Szeredi /* 2805d18e9008SMiklos Szeredi * We didn't have the inode before the open, so check open permission 2806d18e9008SMiklos Szeredi * here. 2807d18e9008SMiklos Szeredi */ 280803da633aSAl Viro acc_mode = op->acc_mode; 280903da633aSAl Viro if (*opened & FILE_CREATED) { 281003da633aSAl Viro WARN_ON(!(open_flag & O_CREAT)); 281103da633aSAl Viro fsnotify_create(dir, dentry); 281203da633aSAl Viro acc_mode = MAY_OPEN; 281303da633aSAl Viro } 28142675a4ebSAl Viro error = may_open(&file->f_path, acc_mode, open_flag); 28152675a4ebSAl Viro if (error) 28162675a4ebSAl Viro fput(file); 2817d18e9008SMiklos Szeredi 2818d18e9008SMiklos Szeredi out: 2819d18e9008SMiklos Szeredi dput(dentry); 28202675a4ebSAl Viro return error; 2821d18e9008SMiklos Szeredi 2822d18e9008SMiklos Szeredi no_open: 2823d18e9008SMiklos Szeredi if (need_lookup) { 282472bd866aSAl Viro dentry = lookup_real(dir, dentry, nd->flags); 2825d18e9008SMiklos Szeredi if (IS_ERR(dentry)) 28262675a4ebSAl Viro return PTR_ERR(dentry); 2827d18e9008SMiklos Szeredi 2828d18e9008SMiklos Szeredi if (create_error) { 2829d18e9008SMiklos Szeredi int open_flag = op->open_flag; 2830d18e9008SMiklos Szeredi 28312675a4ebSAl Viro error = create_error; 2832d18e9008SMiklos Szeredi if ((open_flag & O_EXCL)) { 2833d18e9008SMiklos Szeredi if (!dentry->d_inode) 2834d18e9008SMiklos Szeredi goto out; 2835d18e9008SMiklos Szeredi } else if (!dentry->d_inode) { 2836d18e9008SMiklos Szeredi goto out; 2837d18e9008SMiklos Szeredi } else if ((open_flag & O_TRUNC) && 2838e36cb0b8SDavid Howells d_is_reg(dentry)) { 2839d18e9008SMiklos Szeredi goto out; 2840d18e9008SMiklos Szeredi } 2841d18e9008SMiklos Szeredi /* will fail later, go on to get the right error */ 2842d18e9008SMiklos Szeredi } 2843d18e9008SMiklos Szeredi } 2844d18e9008SMiklos Szeredi looked_up: 2845d18e9008SMiklos Szeredi path->dentry = dentry; 2846d18e9008SMiklos Szeredi path->mnt = nd->path.mnt; 28472675a4ebSAl Viro return 1; 2848d18e9008SMiklos Szeredi } 2849d18e9008SMiklos Szeredi 285031e6b01fSNick Piggin /* 28511acf0af9SDavid Howells * Look up and maybe create and open the last component. 2852d58ffd35SMiklos Szeredi * 2853d58ffd35SMiklos Szeredi * Must be called with i_mutex held on parent. 2854d58ffd35SMiklos Szeredi * 28551acf0af9SDavid Howells * Returns 0 if the file was successfully atomically created (if necessary) and 28561acf0af9SDavid Howells * opened. In this case the file will be returned attached to @file. 28571acf0af9SDavid Howells * 28581acf0af9SDavid Howells * Returns 1 if the file was not completely opened at this time, though lookups 28591acf0af9SDavid Howells * and creations will have been performed and the dentry returned in @path will 28601acf0af9SDavid Howells * be positive upon return if O_CREAT was specified. If O_CREAT wasn't 28611acf0af9SDavid Howells * specified then a negative dentry may be returned. 28621acf0af9SDavid Howells * 28631acf0af9SDavid Howells * An error code is returned otherwise. 28641acf0af9SDavid Howells * 28651acf0af9SDavid Howells * FILE_CREATE will be set in @*opened if the dentry was created and will be 28661acf0af9SDavid Howells * cleared otherwise prior to returning. 2867d58ffd35SMiklos Szeredi */ 28682675a4ebSAl Viro static int lookup_open(struct nameidata *nd, struct path *path, 286930d90494SAl Viro struct file *file, 2870d58ffd35SMiklos Szeredi const struct open_flags *op, 287164894cf8SAl Viro bool got_write, int *opened) 2872d58ffd35SMiklos Szeredi { 2873d58ffd35SMiklos Szeredi struct dentry *dir = nd->path.dentry; 287454ef4872SMiklos Szeredi struct inode *dir_inode = dir->d_inode; 2875d58ffd35SMiklos Szeredi struct dentry *dentry; 2876d58ffd35SMiklos Szeredi int error; 287754ef4872SMiklos Szeredi bool need_lookup; 2878d58ffd35SMiklos Szeredi 287947237687SAl Viro *opened &= ~FILE_CREATED; 2880201f956eSAl Viro dentry = lookup_dcache(&nd->last, dir, nd->flags, &need_lookup); 2881d58ffd35SMiklos Szeredi if (IS_ERR(dentry)) 28822675a4ebSAl Viro return PTR_ERR(dentry); 2883d58ffd35SMiklos Szeredi 2884d18e9008SMiklos Szeredi /* Cached positive dentry: will open in f_op->open */ 2885d18e9008SMiklos Szeredi if (!need_lookup && dentry->d_inode) 2886d18e9008SMiklos Szeredi goto out_no_open; 2887d18e9008SMiklos Szeredi 2888d18e9008SMiklos Szeredi if ((nd->flags & LOOKUP_OPEN) && dir_inode->i_op->atomic_open) { 288964894cf8SAl Viro return atomic_open(nd, dentry, path, file, op, got_write, 289047237687SAl Viro need_lookup, opened); 2891d18e9008SMiklos Szeredi } 2892d18e9008SMiklos Szeredi 289354ef4872SMiklos Szeredi if (need_lookup) { 289454ef4872SMiklos Szeredi BUG_ON(dentry->d_inode); 289554ef4872SMiklos Szeredi 289672bd866aSAl Viro dentry = lookup_real(dir_inode, dentry, nd->flags); 289754ef4872SMiklos Szeredi if (IS_ERR(dentry)) 28982675a4ebSAl Viro return PTR_ERR(dentry); 289954ef4872SMiklos Szeredi } 290054ef4872SMiklos Szeredi 2901d58ffd35SMiklos Szeredi /* Negative dentry, just create the file */ 2902d58ffd35SMiklos Szeredi if (!dentry->d_inode && (op->open_flag & O_CREAT)) { 2903d58ffd35SMiklos Szeredi umode_t mode = op->mode; 2904d58ffd35SMiklos Szeredi if (!IS_POSIXACL(dir->d_inode)) 2905d58ffd35SMiklos Szeredi mode &= ~current_umask(); 2906d58ffd35SMiklos Szeredi /* 2907d58ffd35SMiklos Szeredi * This write is needed to ensure that a 2908d58ffd35SMiklos Szeredi * rw->ro transition does not occur between 2909d58ffd35SMiklos Szeredi * the time when the file is created and when 2910d58ffd35SMiklos Szeredi * a permanent write count is taken through 2911015c3bbcSMiklos Szeredi * the 'struct file' in finish_open(). 2912d58ffd35SMiklos Szeredi */ 291364894cf8SAl Viro if (!got_write) { 291464894cf8SAl Viro error = -EROFS; 2915d58ffd35SMiklos Szeredi goto out_dput; 291664894cf8SAl Viro } 291747237687SAl Viro *opened |= FILE_CREATED; 2918d58ffd35SMiklos Szeredi error = security_path_mknod(&nd->path, dentry, mode, 0); 2919d58ffd35SMiklos Szeredi if (error) 2920d58ffd35SMiklos Szeredi goto out_dput; 2921312b63fbSAl Viro error = vfs_create(dir->d_inode, dentry, mode, 2922312b63fbSAl Viro nd->flags & LOOKUP_EXCL); 2923d58ffd35SMiklos Szeredi if (error) 2924d58ffd35SMiklos Szeredi goto out_dput; 2925d58ffd35SMiklos Szeredi } 2926d18e9008SMiklos Szeredi out_no_open: 2927d58ffd35SMiklos Szeredi path->dentry = dentry; 2928d58ffd35SMiklos Szeredi path->mnt = nd->path.mnt; 29292675a4ebSAl Viro return 1; 2930d58ffd35SMiklos Szeredi 2931d58ffd35SMiklos Szeredi out_dput: 2932d58ffd35SMiklos Szeredi dput(dentry); 29332675a4ebSAl Viro return error; 2934d58ffd35SMiklos Szeredi } 2935d58ffd35SMiklos Szeredi 2936d58ffd35SMiklos Szeredi /* 2937fe2d35ffSAl Viro * Handle the last step of open() 293831e6b01fSNick Piggin */ 2939896475d5SAl Viro static int do_last(struct nameidata *nd, 294030d90494SAl Viro struct file *file, const struct open_flags *op, 2941669abf4eSJeff Layton int *opened, struct filename *name) 2942fb1cc555SAl Viro { 2943a1e28038SAl Viro struct dentry *dir = nd->path.dentry; 2944ca344a89SAl Viro int open_flag = op->open_flag; 294577d660a8SMiklos Szeredi bool will_truncate = (open_flag & O_TRUNC) != 0; 294664894cf8SAl Viro bool got_write = false; 2947bcda7652SAl Viro int acc_mode = op->acc_mode; 2948a1eb3315SMiklos Szeredi struct inode *inode; 294916b1c1cdSMiklos Szeredi struct path save_parent = { .dentry = NULL, .mnt = NULL }; 2950896475d5SAl Viro struct path path; 295116b1c1cdSMiklos Szeredi bool retried = false; 295216c2cd71SAl Viro int error; 2953fb1cc555SAl Viro 2954c3e380b0SAl Viro nd->flags &= ~LOOKUP_PARENT; 2955c3e380b0SAl Viro nd->flags |= op->intent; 2956c3e380b0SAl Viro 2957bc77daa7SAl Viro if (nd->last_type != LAST_NORM) { 2958fe2d35ffSAl Viro error = handle_dots(nd, nd->last_type); 2959fe2d35ffSAl Viro if (error) 29602675a4ebSAl Viro return error; 2961e83db167SMiklos Szeredi goto finish_open; 29621f36f774SAl Viro } 2963a2c36b45SAl Viro 2964ca344a89SAl Viro if (!(open_flag & O_CREAT)) { 2965fe2d35ffSAl Viro if (nd->last.name[nd->last.len]) 2966fe2d35ffSAl Viro nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; 2967fe2d35ffSAl Viro /* we _can_ be in RCU mode here */ 2968896475d5SAl Viro error = lookup_fast(nd, &path, &inode); 296971574865SMiklos Szeredi if (likely(!error)) 297071574865SMiklos Szeredi goto finish_lookup; 297171574865SMiklos Szeredi 2972ce57dfc1SAl Viro if (error < 0) 29732675a4ebSAl Viro goto out; 2974a1eb3315SMiklos Szeredi 297537d7fffcSMiklos Szeredi BUG_ON(nd->inode != dir->d_inode); 2976b6183df7SMiklos Szeredi } else { 2977fe2d35ffSAl Viro /* create side of things */ 2978a3fbbde7SAl Viro /* 2979b6183df7SMiklos Szeredi * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED 2980b6183df7SMiklos Szeredi * has been cleared when we got to the last component we are 2981b6183df7SMiklos Szeredi * about to look up 2982a3fbbde7SAl Viro */ 29839f1fafeeSAl Viro error = complete_walk(nd); 29849f1fafeeSAl Viro if (error) 29852675a4ebSAl Viro return error; 2986fe2d35ffSAl Viro 298733e2208aSJeff Layton audit_inode(name, dir, LOOKUP_PARENT); 298816c2cd71SAl Viro error = -EISDIR; 29891f36f774SAl Viro /* trailing slashes? */ 299031e6b01fSNick Piggin if (nd->last.name[nd->last.len]) 29912675a4ebSAl Viro goto out; 2992b6183df7SMiklos Szeredi } 29931f36f774SAl Viro 299416b1c1cdSMiklos Szeredi retry_lookup: 299564894cf8SAl Viro if (op->open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) { 299664894cf8SAl Viro error = mnt_want_write(nd->path.mnt); 299764894cf8SAl Viro if (!error) 299864894cf8SAl Viro got_write = true; 299964894cf8SAl Viro /* 300064894cf8SAl Viro * do _not_ fail yet - we might not need that or fail with 300164894cf8SAl Viro * a different error; let lookup_open() decide; we'll be 300264894cf8SAl Viro * dropping this one anyway. 300364894cf8SAl Viro */ 300464894cf8SAl Viro } 3005a1e28038SAl Viro mutex_lock(&dir->d_inode->i_mutex); 3006896475d5SAl Viro error = lookup_open(nd, &path, file, op, got_write, opened); 3007fb1cc555SAl Viro mutex_unlock(&dir->d_inode->i_mutex); 3008fb1cc555SAl Viro 30092675a4ebSAl Viro if (error <= 0) { 30102675a4ebSAl Viro if (error) 3011d58ffd35SMiklos Szeredi goto out; 30126c0d46c4SAl Viro 301347237687SAl Viro if ((*opened & FILE_CREATED) || 3014496ad9aaSAl Viro !S_ISREG(file_inode(file)->i_mode)) 301577d660a8SMiklos Szeredi will_truncate = false; 3016d18e9008SMiklos Szeredi 3017adb5c247SJeff Layton audit_inode(name, file->f_path.dentry, 0); 3018d18e9008SMiklos Szeredi goto opened; 3019d18e9008SMiklos Szeredi } 3020d18e9008SMiklos Szeredi 302147237687SAl Viro if (*opened & FILE_CREATED) { 30229b44f1b3SAl Viro /* Don't check for write permission, don't truncate */ 3023ca344a89SAl Viro open_flag &= ~O_TRUNC; 302477d660a8SMiklos Szeredi will_truncate = false; 3025bcda7652SAl Viro acc_mode = MAY_OPEN; 3026896475d5SAl Viro path_to_nameidata(&path, nd); 3027e83db167SMiklos Szeredi goto finish_open_created; 3028fb1cc555SAl Viro } 3029fb1cc555SAl Viro 3030fb1cc555SAl Viro /* 30313134f37eSJeff Layton * create/update audit record if it already exists. 3032fb1cc555SAl Viro */ 3033896475d5SAl Viro if (d_is_positive(path.dentry)) 3034896475d5SAl Viro audit_inode(name, path.dentry, 0); 3035fb1cc555SAl Viro 3036d18e9008SMiklos Szeredi /* 3037d18e9008SMiklos Szeredi * If atomic_open() acquired write access it is dropped now due to 3038d18e9008SMiklos Szeredi * possible mount and symlink following (this might be optimized away if 3039d18e9008SMiklos Szeredi * necessary...) 3040d18e9008SMiklos Szeredi */ 304164894cf8SAl Viro if (got_write) { 3042d18e9008SMiklos Szeredi mnt_drop_write(nd->path.mnt); 304364894cf8SAl Viro got_write = false; 3044d18e9008SMiklos Szeredi } 3045d18e9008SMiklos Szeredi 3046fb1cc555SAl Viro error = -EEXIST; 3047f8310c59SAl Viro if ((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT)) 3048fb1cc555SAl Viro goto exit_dput; 3049fb1cc555SAl Viro 3050896475d5SAl Viro error = follow_managed(&path, nd->flags); 30519875cf80SDavid Howells if (error < 0) 3052fb1cc555SAl Viro goto exit_dput; 3053fb1cc555SAl Viro 3054a3fbbde7SAl Viro if (error) 3055a3fbbde7SAl Viro nd->flags |= LOOKUP_JUMPED; 3056a3fbbde7SAl Viro 3057decf3400SMiklos Szeredi BUG_ON(nd->flags & LOOKUP_RCU); 3058896475d5SAl Viro inode = path.dentry->d_inode; 3059fb1cc555SAl Viro error = -ENOENT; 3060896475d5SAl Viro if (d_is_negative(path.dentry)) { 3061896475d5SAl Viro path_to_nameidata(&path, nd); 30622675a4ebSAl Viro goto out; 306354c33e7fSMiklos Szeredi } 3064766c4cbfSAl Viro finish_lookup: 3065896475d5SAl Viro if (should_follow_link(path.dentry, nd->flags & LOOKUP_FOLLOW)) { 3066d45ea867SMiklos Szeredi if (nd->flags & LOOKUP_RCU) { 3067896475d5SAl Viro if (unlikely(nd->path.mnt != path.mnt || 3068896475d5SAl Viro unlazy_walk(nd, path.dentry))) { 3069d45ea867SMiklos Szeredi error = -ECHILD; 30702675a4ebSAl Viro goto out; 3071d45ea867SMiklos Szeredi } 3072d45ea867SMiklos Szeredi } 3073896475d5SAl Viro BUG_ON(inode != path.dentry->d_inode); 3074896475d5SAl Viro nd->link = path; 30752675a4ebSAl Viro return 1; 3076d45ea867SMiklos Szeredi } 3077fb1cc555SAl Viro 3078896475d5SAl Viro if (unlikely(d_is_symlink(path.dentry)) && !(open_flag & O_PATH)) { 3079896475d5SAl Viro path_to_nameidata(&path, nd); 3080a5cfe2d5SAl Viro error = -ELOOP; 3081a5cfe2d5SAl Viro goto out; 3082a5cfe2d5SAl Viro } 3083a5cfe2d5SAl Viro 3084896475d5SAl Viro if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) { 3085896475d5SAl Viro path_to_nameidata(&path, nd); 308616b1c1cdSMiklos Szeredi } else { 308716b1c1cdSMiklos Szeredi save_parent.dentry = nd->path.dentry; 3088896475d5SAl Viro save_parent.mnt = mntget(path.mnt); 3089896475d5SAl Viro nd->path.dentry = path.dentry; 309016b1c1cdSMiklos Szeredi 309116b1c1cdSMiklos Szeredi } 3092decf3400SMiklos Szeredi nd->inode = inode; 3093a3fbbde7SAl Viro /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */ 3094bc77daa7SAl Viro finish_open: 3095a3fbbde7SAl Viro error = complete_walk(nd); 309616b1c1cdSMiklos Szeredi if (error) { 309716b1c1cdSMiklos Szeredi path_put(&save_parent); 30982675a4ebSAl Viro return error; 309916b1c1cdSMiklos Szeredi } 3100bc77daa7SAl Viro audit_inode(name, nd->path.dentry, 0); 3101fb1cc555SAl Viro error = -EISDIR; 310244b1d530SMiklos Szeredi if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry)) 31032675a4ebSAl Viro goto out; 3104af2f5542SMiklos Szeredi error = -ENOTDIR; 310544b1d530SMiklos Szeredi if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) 31062675a4ebSAl Viro goto out; 31074bbcbd3bSDavid Howells if (!d_is_reg(nd->path.dentry)) 310877d660a8SMiklos Szeredi will_truncate = false; 31096c0d46c4SAl Viro 31100f9d1a10SAl Viro if (will_truncate) { 31110f9d1a10SAl Viro error = mnt_want_write(nd->path.mnt); 31120f9d1a10SAl Viro if (error) 31132675a4ebSAl Viro goto out; 311464894cf8SAl Viro got_write = true; 31150f9d1a10SAl Viro } 3116e83db167SMiklos Szeredi finish_open_created: 3117bcda7652SAl Viro error = may_open(&nd->path, acc_mode, open_flag); 3118ca344a89SAl Viro if (error) 31192675a4ebSAl Viro goto out; 31204aa7c634SMiklos Szeredi 31214aa7c634SMiklos Szeredi BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */ 31224aa7c634SMiklos Szeredi error = vfs_open(&nd->path, file, current_cred()); 31234aa7c634SMiklos Szeredi if (!error) { 31244aa7c634SMiklos Szeredi *opened |= FILE_OPENED; 31254aa7c634SMiklos Szeredi } else { 312630d90494SAl Viro if (error == -EOPENSTALE) 3127f60dc3dbSMiklos Szeredi goto stale_open; 3128015c3bbcSMiklos Szeredi goto out; 3129f60dc3dbSMiklos Szeredi } 3130a8277b9bSMiklos Szeredi opened: 31312675a4ebSAl Viro error = open_check_o_direct(file); 3132015c3bbcSMiklos Szeredi if (error) 3133015c3bbcSMiklos Szeredi goto exit_fput; 31343034a146SDmitry Kasatkin error = ima_file_check(file, op->acc_mode, *opened); 3135aa4caadbSMiklos Szeredi if (error) 3136aa4caadbSMiklos Szeredi goto exit_fput; 3137aa4caadbSMiklos Szeredi 31380f9d1a10SAl Viro if (will_truncate) { 31392675a4ebSAl Viro error = handle_truncate(file); 3140aa4caadbSMiklos Szeredi if (error) 3141aa4caadbSMiklos Szeredi goto exit_fput; 31420f9d1a10SAl Viro } 3143ca344a89SAl Viro out: 314464894cf8SAl Viro if (got_write) 31450f9d1a10SAl Viro mnt_drop_write(nd->path.mnt); 314616b1c1cdSMiklos Szeredi path_put(&save_parent); 3147e276ae67SMiklos Szeredi terminate_walk(nd); 31482675a4ebSAl Viro return error; 3149fb1cc555SAl Viro 3150fb1cc555SAl Viro exit_dput: 3151896475d5SAl Viro path_put_conditional(&path, nd); 3152ca344a89SAl Viro goto out; 3153015c3bbcSMiklos Szeredi exit_fput: 31542675a4ebSAl Viro fput(file); 31552675a4ebSAl Viro goto out; 3156015c3bbcSMiklos Szeredi 3157f60dc3dbSMiklos Szeredi stale_open: 3158f60dc3dbSMiklos Szeredi /* If no saved parent or already retried then can't retry */ 3159f60dc3dbSMiklos Szeredi if (!save_parent.dentry || retried) 3160f60dc3dbSMiklos Szeredi goto out; 3161f60dc3dbSMiklos Szeredi 3162f60dc3dbSMiklos Szeredi BUG_ON(save_parent.dentry != dir); 3163f60dc3dbSMiklos Szeredi path_put(&nd->path); 3164f60dc3dbSMiklos Szeredi nd->path = save_parent; 3165f60dc3dbSMiklos Szeredi nd->inode = dir->d_inode; 3166f60dc3dbSMiklos Szeredi save_parent.mnt = NULL; 3167f60dc3dbSMiklos Szeredi save_parent.dentry = NULL; 316864894cf8SAl Viro if (got_write) { 3169f60dc3dbSMiklos Szeredi mnt_drop_write(nd->path.mnt); 317064894cf8SAl Viro got_write = false; 3171f60dc3dbSMiklos Szeredi } 3172f60dc3dbSMiklos Szeredi retried = true; 3173f60dc3dbSMiklos Szeredi goto retry_lookup; 3174fb1cc555SAl Viro } 3175fb1cc555SAl Viro 317660545d0dSAl Viro static int do_tmpfile(int dfd, struct filename *pathname, 317760545d0dSAl Viro struct nameidata *nd, int flags, 317860545d0dSAl Viro const struct open_flags *op, 317960545d0dSAl Viro struct file *file, int *opened) 318060545d0dSAl Viro { 318160545d0dSAl Viro static const struct qstr name = QSTR_INIT("/", 1); 318260545d0dSAl Viro struct dentry *dentry, *child; 318360545d0dSAl Viro struct inode *dir; 31845eb6b495SAl Viro int error = path_lookupat(dfd, pathname, 318560545d0dSAl Viro flags | LOOKUP_DIRECTORY, nd); 318660545d0dSAl Viro if (unlikely(error)) 318760545d0dSAl Viro return error; 318860545d0dSAl Viro error = mnt_want_write(nd->path.mnt); 318960545d0dSAl Viro if (unlikely(error)) 319060545d0dSAl Viro goto out; 319160545d0dSAl Viro /* we want directory to be writable */ 319260545d0dSAl Viro error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC); 319360545d0dSAl Viro if (error) 319460545d0dSAl Viro goto out2; 319560545d0dSAl Viro dentry = nd->path.dentry; 319660545d0dSAl Viro dir = dentry->d_inode; 319760545d0dSAl Viro if (!dir->i_op->tmpfile) { 319860545d0dSAl Viro error = -EOPNOTSUPP; 319960545d0dSAl Viro goto out2; 320060545d0dSAl Viro } 320160545d0dSAl Viro child = d_alloc(dentry, &name); 320260545d0dSAl Viro if (unlikely(!child)) { 320360545d0dSAl Viro error = -ENOMEM; 320460545d0dSAl Viro goto out2; 320560545d0dSAl Viro } 320660545d0dSAl Viro nd->flags &= ~LOOKUP_DIRECTORY; 320760545d0dSAl Viro nd->flags |= op->intent; 320860545d0dSAl Viro dput(nd->path.dentry); 320960545d0dSAl Viro nd->path.dentry = child; 321060545d0dSAl Viro error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode); 321160545d0dSAl Viro if (error) 321260545d0dSAl Viro goto out2; 321360545d0dSAl Viro audit_inode(pathname, nd->path.dentry, 0); 321469a91c23SEric Rannaud /* Don't check for other permissions, the inode was just created */ 321569a91c23SEric Rannaud error = may_open(&nd->path, MAY_OPEN, op->open_flag); 321660545d0dSAl Viro if (error) 321760545d0dSAl Viro goto out2; 321860545d0dSAl Viro file->f_path.mnt = nd->path.mnt; 321960545d0dSAl Viro error = finish_open(file, nd->path.dentry, NULL, opened); 322060545d0dSAl Viro if (error) 322160545d0dSAl Viro goto out2; 322260545d0dSAl Viro error = open_check_o_direct(file); 3223f4e0c30cSAl Viro if (error) { 322460545d0dSAl Viro fput(file); 3225f4e0c30cSAl Viro } else if (!(op->open_flag & O_EXCL)) { 3226f4e0c30cSAl Viro struct inode *inode = file_inode(file); 3227f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3228f4e0c30cSAl Viro inode->i_state |= I_LINKABLE; 3229f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3230f4e0c30cSAl Viro } 323160545d0dSAl Viro out2: 323260545d0dSAl Viro mnt_drop_write(nd->path.mnt); 323360545d0dSAl Viro out: 323460545d0dSAl Viro path_put(&nd->path); 323560545d0dSAl Viro return error; 323660545d0dSAl Viro } 323760545d0dSAl Viro 3238669abf4eSJeff Layton static struct file *path_openat(int dfd, struct filename *pathname, 323973d049a4SAl Viro struct nameidata *nd, const struct open_flags *op, int flags) 32401da177e4SLinus Torvalds { 324130d90494SAl Viro struct file *file; 324247237687SAl Viro int opened = 0; 324313aab428SAl Viro int error; 324431e6b01fSNick Piggin 324530d90494SAl Viro file = get_empty_filp(); 32461afc99beSAl Viro if (IS_ERR(file)) 32471afc99beSAl Viro return file; 324831e6b01fSNick Piggin 324930d90494SAl Viro file->f_flags = op->open_flag; 325031e6b01fSNick Piggin 3251bb458c64SAl Viro if (unlikely(file->f_flags & __O_TMPFILE)) { 325260545d0dSAl Viro error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened); 3253f15133dfSAl Viro goto out2; 325460545d0dSAl Viro } 325560545d0dSAl Viro 32566e8a1f87SAl Viro error = path_init(dfd, pathname, flags, nd); 325731e6b01fSNick Piggin if (unlikely(error)) 32582675a4ebSAl Viro goto out; 32591da177e4SLinus Torvalds 3260896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 32612675a4ebSAl Viro while (unlikely(error > 0)) { /* trailing symlink */ 3262caa85634SAl Viro struct path link = nd->link; 3263def4af30SAl Viro void *cookie; 326473d049a4SAl Viro nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL); 326595fa25d9SAl Viro error = trailing_symlink(&link, nd, &cookie); 3266c3e380b0SAl Viro if (unlikely(error)) 32672675a4ebSAl Viro break; 3268896475d5SAl Viro error = do_last(nd, file, op, &opened, pathname); 3269574197e0SAl Viro put_link(nd, &link, cookie); 3270806b681cSAl Viro } 327110fa8e62SAl Viro out: 3272893b7775SAl Viro path_cleanup(nd); 3273f15133dfSAl Viro out2: 32742675a4ebSAl Viro if (!(opened & FILE_OPENED)) { 32752675a4ebSAl Viro BUG_ON(!error); 327630d90494SAl Viro put_filp(file); 3277015c3bbcSMiklos Szeredi } 32782675a4ebSAl Viro if (unlikely(error)) { 32792675a4ebSAl Viro if (error == -EOPENSTALE) { 32802675a4ebSAl Viro if (flags & LOOKUP_RCU) 32812675a4ebSAl Viro error = -ECHILD; 32822675a4ebSAl Viro else 32832675a4ebSAl Viro error = -ESTALE; 32842675a4ebSAl Viro } 32852675a4ebSAl Viro file = ERR_PTR(error); 32862675a4ebSAl Viro } 32872675a4ebSAl Viro return file; 3288de459215SKirill Korotaev } 32891da177e4SLinus Torvalds 3290669abf4eSJeff Layton struct file *do_filp_open(int dfd, struct filename *pathname, 3291f9652e10SAl Viro const struct open_flags *op) 329213aab428SAl Viro { 329373d049a4SAl Viro struct nameidata nd; 3294f9652e10SAl Viro int flags = op->lookup_flags; 329513aab428SAl Viro struct file *filp; 329613aab428SAl Viro 329773d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU); 329813aab428SAl Viro if (unlikely(filp == ERR_PTR(-ECHILD))) 329973d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags); 330013aab428SAl Viro if (unlikely(filp == ERR_PTR(-ESTALE))) 330173d049a4SAl Viro filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL); 330213aab428SAl Viro return filp; 330313aab428SAl Viro } 330413aab428SAl Viro 330573d049a4SAl Viro struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt, 3306f9652e10SAl Viro const char *name, const struct open_flags *op) 330773d049a4SAl Viro { 330873d049a4SAl Viro struct nameidata nd; 330973d049a4SAl Viro struct file *file; 331051689104SPaul Moore struct filename *filename; 3311f9652e10SAl Viro int flags = op->lookup_flags | LOOKUP_ROOT; 331273d049a4SAl Viro 331373d049a4SAl Viro nd.root.mnt = mnt; 331473d049a4SAl Viro nd.root.dentry = dentry; 331573d049a4SAl Viro 3316b18825a7SDavid Howells if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN) 331773d049a4SAl Viro return ERR_PTR(-ELOOP); 331873d049a4SAl Viro 331951689104SPaul Moore filename = getname_kernel(name); 332051689104SPaul Moore if (unlikely(IS_ERR(filename))) 332151689104SPaul Moore return ERR_CAST(filename); 332251689104SPaul Moore 332351689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU); 332473d049a4SAl Viro if (unlikely(file == ERR_PTR(-ECHILD))) 332551689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags); 332673d049a4SAl Viro if (unlikely(file == ERR_PTR(-ESTALE))) 332751689104SPaul Moore file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL); 332851689104SPaul Moore putname(filename); 332973d049a4SAl Viro return file; 333073d049a4SAl Viro } 333173d049a4SAl Viro 3332fa14a0b8SAl Viro static struct dentry *filename_create(int dfd, struct filename *name, 33331ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 33341da177e4SLinus Torvalds { 3335c663e5d8SChristoph Hellwig struct dentry *dentry = ERR_PTR(-EEXIST); 3336ed75e95dSAl Viro struct nameidata nd; 3337c30dabfeSJan Kara int err2; 33381ac12b4bSJeff Layton int error; 33391ac12b4bSJeff Layton bool is_dir = (lookup_flags & LOOKUP_DIRECTORY); 33401ac12b4bSJeff Layton 33411ac12b4bSJeff Layton /* 33421ac12b4bSJeff Layton * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any 33431ac12b4bSJeff Layton * other flags passed in are ignored! 33441ac12b4bSJeff Layton */ 33451ac12b4bSJeff Layton lookup_flags &= LOOKUP_REVAL; 33461ac12b4bSJeff Layton 3347fa14a0b8SAl Viro error = filename_lookup(dfd, name, LOOKUP_PARENT|lookup_flags, &nd); 3348ed75e95dSAl Viro if (error) 3349ed75e95dSAl Viro return ERR_PTR(error); 33501da177e4SLinus Torvalds 3351c663e5d8SChristoph Hellwig /* 3352c663e5d8SChristoph Hellwig * Yucky last component or no last component at all? 3353c663e5d8SChristoph Hellwig * (foo/., foo/.., /////) 3354c663e5d8SChristoph Hellwig */ 3355ed75e95dSAl Viro if (nd.last_type != LAST_NORM) 3356ed75e95dSAl Viro goto out; 3357ed75e95dSAl Viro nd.flags &= ~LOOKUP_PARENT; 3358ed75e95dSAl Viro nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL; 3359c663e5d8SChristoph Hellwig 3360c30dabfeSJan Kara /* don't fail immediately if it's r/o, at least try to report other errors */ 3361c30dabfeSJan Kara err2 = mnt_want_write(nd.path.mnt); 3362c663e5d8SChristoph Hellwig /* 3363c663e5d8SChristoph Hellwig * Do the final lookup. 3364c663e5d8SChristoph Hellwig */ 3365ed75e95dSAl Viro mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 33666a9f40d6SAl Viro dentry = __lookup_hash(&nd.last, nd.path.dentry, nd.flags); 33671da177e4SLinus Torvalds if (IS_ERR(dentry)) 3368a8104a9fSAl Viro goto unlock; 3369c663e5d8SChristoph Hellwig 3370a8104a9fSAl Viro error = -EEXIST; 3371b18825a7SDavid Howells if (d_is_positive(dentry)) 3372a8104a9fSAl Viro goto fail; 3373b18825a7SDavid Howells 3374c663e5d8SChristoph Hellwig /* 3375c663e5d8SChristoph Hellwig * Special case - lookup gave negative, but... we had foo/bar/ 3376c663e5d8SChristoph Hellwig * From the vfs_mknod() POV we just have a negative dentry - 3377c663e5d8SChristoph Hellwig * all is fine. Let's be bastards - you had / on the end, you've 3378c663e5d8SChristoph Hellwig * been asking for (non-existent) directory. -ENOENT for you. 3379c663e5d8SChristoph Hellwig */ 3380ed75e95dSAl Viro if (unlikely(!is_dir && nd.last.name[nd.last.len])) { 3381a8104a9fSAl Viro error = -ENOENT; 3382ed75e95dSAl Viro goto fail; 3383e9baf6e5SAl Viro } 3384c30dabfeSJan Kara if (unlikely(err2)) { 3385c30dabfeSJan Kara error = err2; 3386a8104a9fSAl Viro goto fail; 3387c30dabfeSJan Kara } 3388ed75e95dSAl Viro *path = nd.path; 3389e9baf6e5SAl Viro return dentry; 33901da177e4SLinus Torvalds fail: 3391a8104a9fSAl Viro dput(dentry); 3392a8104a9fSAl Viro dentry = ERR_PTR(error); 3393a8104a9fSAl Viro unlock: 3394dae6ad8fSAl Viro mutex_unlock(&nd.path.dentry->d_inode->i_mutex); 3395c30dabfeSJan Kara if (!err2) 3396c30dabfeSJan Kara mnt_drop_write(nd.path.mnt); 3397ed75e95dSAl Viro out: 3398dae6ad8fSAl Viro path_put(&nd.path); 3399ed75e95dSAl Viro return dentry; 3400dae6ad8fSAl Viro } 3401fa14a0b8SAl Viro 3402fa14a0b8SAl Viro struct dentry *kern_path_create(int dfd, const char *pathname, 3403fa14a0b8SAl Viro struct path *path, unsigned int lookup_flags) 3404fa14a0b8SAl Viro { 340551689104SPaul Moore struct filename *filename = getname_kernel(pathname); 340651689104SPaul Moore struct dentry *res; 340751689104SPaul Moore 340851689104SPaul Moore if (IS_ERR(filename)) 340951689104SPaul Moore return ERR_CAST(filename); 341051689104SPaul Moore res = filename_create(dfd, filename, path, lookup_flags); 341151689104SPaul Moore putname(filename); 341251689104SPaul Moore return res; 3413fa14a0b8SAl Viro } 3414dae6ad8fSAl Viro EXPORT_SYMBOL(kern_path_create); 3415dae6ad8fSAl Viro 3416921a1650SAl Viro void done_path_create(struct path *path, struct dentry *dentry) 3417921a1650SAl Viro { 3418921a1650SAl Viro dput(dentry); 3419921a1650SAl Viro mutex_unlock(&path->dentry->d_inode->i_mutex); 3420a8104a9fSAl Viro mnt_drop_write(path->mnt); 3421921a1650SAl Viro path_put(path); 3422921a1650SAl Viro } 3423921a1650SAl Viro EXPORT_SYMBOL(done_path_create); 3424921a1650SAl Viro 34251ac12b4bSJeff Layton struct dentry *user_path_create(int dfd, const char __user *pathname, 34261ac12b4bSJeff Layton struct path *path, unsigned int lookup_flags) 3427dae6ad8fSAl Viro { 342891a27b2aSJeff Layton struct filename *tmp = getname(pathname); 3429dae6ad8fSAl Viro struct dentry *res; 3430dae6ad8fSAl Viro if (IS_ERR(tmp)) 3431dae6ad8fSAl Viro return ERR_CAST(tmp); 3432fa14a0b8SAl Viro res = filename_create(dfd, tmp, path, lookup_flags); 3433dae6ad8fSAl Viro putname(tmp); 3434dae6ad8fSAl Viro return res; 3435dae6ad8fSAl Viro } 3436dae6ad8fSAl Viro EXPORT_SYMBOL(user_path_create); 3437dae6ad8fSAl Viro 34381a67aafbSAl Viro int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 34391da177e4SLinus Torvalds { 3440a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 34411da177e4SLinus Torvalds 34421da177e4SLinus Torvalds if (error) 34431da177e4SLinus Torvalds return error; 34441da177e4SLinus Torvalds 3445975d6b39SEric W. Biederman if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) 34461da177e4SLinus Torvalds return -EPERM; 34471da177e4SLinus Torvalds 3448acfa4380SAl Viro if (!dir->i_op->mknod) 34491da177e4SLinus Torvalds return -EPERM; 34501da177e4SLinus Torvalds 345108ce5f16SSerge E. Hallyn error = devcgroup_inode_mknod(mode, dev); 345208ce5f16SSerge E. Hallyn if (error) 345308ce5f16SSerge E. Hallyn return error; 345408ce5f16SSerge E. Hallyn 34551da177e4SLinus Torvalds error = security_inode_mknod(dir, dentry, mode, dev); 34561da177e4SLinus Torvalds if (error) 34571da177e4SLinus Torvalds return error; 34581da177e4SLinus Torvalds 34591da177e4SLinus Torvalds error = dir->i_op->mknod(dir, dentry, mode, dev); 3460a74574aaSStephen Smalley if (!error) 3461f38aa942SAmy Griffis fsnotify_create(dir, dentry); 34621da177e4SLinus Torvalds return error; 34631da177e4SLinus Torvalds } 34644d359507SAl Viro EXPORT_SYMBOL(vfs_mknod); 34651da177e4SLinus Torvalds 3466f69aac00SAl Viro static int may_mknod(umode_t mode) 3467463c3197SDave Hansen { 3468463c3197SDave Hansen switch (mode & S_IFMT) { 3469463c3197SDave Hansen case S_IFREG: 3470463c3197SDave Hansen case S_IFCHR: 3471463c3197SDave Hansen case S_IFBLK: 3472463c3197SDave Hansen case S_IFIFO: 3473463c3197SDave Hansen case S_IFSOCK: 3474463c3197SDave Hansen case 0: /* zero mode translates to S_IFREG */ 3475463c3197SDave Hansen return 0; 3476463c3197SDave Hansen case S_IFDIR: 3477463c3197SDave Hansen return -EPERM; 3478463c3197SDave Hansen default: 3479463c3197SDave Hansen return -EINVAL; 3480463c3197SDave Hansen } 3481463c3197SDave Hansen } 3482463c3197SDave Hansen 34838208a22bSAl Viro SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode, 34842e4d0924SHeiko Carstens unsigned, dev) 34851da177e4SLinus Torvalds { 34861da177e4SLinus Torvalds struct dentry *dentry; 3487dae6ad8fSAl Viro struct path path; 3488dae6ad8fSAl Viro int error; 3489972567f1SJeff Layton unsigned int lookup_flags = 0; 34901da177e4SLinus Torvalds 34918e4bfca1SAl Viro error = may_mknod(mode); 34928e4bfca1SAl Viro if (error) 34938e4bfca1SAl Viro return error; 3494972567f1SJeff Layton retry: 3495972567f1SJeff Layton dentry = user_path_create(dfd, filename, &path, lookup_flags); 3496dae6ad8fSAl Viro if (IS_ERR(dentry)) 3497dae6ad8fSAl Viro return PTR_ERR(dentry); 34982ad94ae6SAl Viro 3499dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3500ce3b0f8dSAl Viro mode &= ~current_umask(); 3501dae6ad8fSAl Viro error = security_path_mknod(&path, dentry, mode, dev); 3502be6d3e56SKentaro Takeda if (error) 3503a8104a9fSAl Viro goto out; 35041da177e4SLinus Torvalds switch (mode & S_IFMT) { 35051da177e4SLinus Torvalds case 0: case S_IFREG: 3506312b63fbSAl Viro error = vfs_create(path.dentry->d_inode,dentry,mode,true); 35071da177e4SLinus Torvalds break; 35081da177e4SLinus Torvalds case S_IFCHR: case S_IFBLK: 3509dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode, 35101da177e4SLinus Torvalds new_decode_dev(dev)); 35111da177e4SLinus Torvalds break; 35121da177e4SLinus Torvalds case S_IFIFO: case S_IFSOCK: 3513dae6ad8fSAl Viro error = vfs_mknod(path.dentry->d_inode,dentry,mode,0); 35141da177e4SLinus Torvalds break; 35151da177e4SLinus Torvalds } 3516a8104a9fSAl Viro out: 3517921a1650SAl Viro done_path_create(&path, dentry); 3518972567f1SJeff Layton if (retry_estale(error, lookup_flags)) { 3519972567f1SJeff Layton lookup_flags |= LOOKUP_REVAL; 3520972567f1SJeff Layton goto retry; 3521972567f1SJeff Layton } 35221da177e4SLinus Torvalds return error; 35231da177e4SLinus Torvalds } 35241da177e4SLinus Torvalds 35258208a22bSAl Viro SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev) 35265590ff0dSUlrich Drepper { 35275590ff0dSUlrich Drepper return sys_mknodat(AT_FDCWD, filename, mode, dev); 35285590ff0dSUlrich Drepper } 35295590ff0dSUlrich Drepper 353018bb1db3SAl Viro int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) 35311da177e4SLinus Torvalds { 3532a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 35338de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 35341da177e4SLinus Torvalds 35351da177e4SLinus Torvalds if (error) 35361da177e4SLinus Torvalds return error; 35371da177e4SLinus Torvalds 3538acfa4380SAl Viro if (!dir->i_op->mkdir) 35391da177e4SLinus Torvalds return -EPERM; 35401da177e4SLinus Torvalds 35411da177e4SLinus Torvalds mode &= (S_IRWXUGO|S_ISVTX); 35421da177e4SLinus Torvalds error = security_inode_mkdir(dir, dentry, mode); 35431da177e4SLinus Torvalds if (error) 35441da177e4SLinus Torvalds return error; 35451da177e4SLinus Torvalds 35468de52778SAl Viro if (max_links && dir->i_nlink >= max_links) 35478de52778SAl Viro return -EMLINK; 35488de52778SAl Viro 35491da177e4SLinus Torvalds error = dir->i_op->mkdir(dir, dentry, mode); 3550a74574aaSStephen Smalley if (!error) 3551f38aa942SAmy Griffis fsnotify_mkdir(dir, dentry); 35521da177e4SLinus Torvalds return error; 35531da177e4SLinus Torvalds } 35544d359507SAl Viro EXPORT_SYMBOL(vfs_mkdir); 35551da177e4SLinus Torvalds 3556a218d0fdSAl Viro SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode) 35571da177e4SLinus Torvalds { 35586902d925SDave Hansen struct dentry *dentry; 3559dae6ad8fSAl Viro struct path path; 3560dae6ad8fSAl Viro int error; 3561b76d8b82SJeff Layton unsigned int lookup_flags = LOOKUP_DIRECTORY; 35621da177e4SLinus Torvalds 3563b76d8b82SJeff Layton retry: 3564b76d8b82SJeff Layton dentry = user_path_create(dfd, pathname, &path, lookup_flags); 35656902d925SDave Hansen if (IS_ERR(dentry)) 3566dae6ad8fSAl Viro return PTR_ERR(dentry); 35676902d925SDave Hansen 3568dae6ad8fSAl Viro if (!IS_POSIXACL(path.dentry->d_inode)) 3569ce3b0f8dSAl Viro mode &= ~current_umask(); 3570dae6ad8fSAl Viro error = security_path_mkdir(&path, dentry, mode); 3571a8104a9fSAl Viro if (!error) 3572dae6ad8fSAl Viro error = vfs_mkdir(path.dentry->d_inode, dentry, mode); 3573921a1650SAl Viro done_path_create(&path, dentry); 3574b76d8b82SJeff Layton if (retry_estale(error, lookup_flags)) { 3575b76d8b82SJeff Layton lookup_flags |= LOOKUP_REVAL; 3576b76d8b82SJeff Layton goto retry; 3577b76d8b82SJeff Layton } 35781da177e4SLinus Torvalds return error; 35791da177e4SLinus Torvalds } 35801da177e4SLinus Torvalds 3581a218d0fdSAl Viro SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode) 35825590ff0dSUlrich Drepper { 35835590ff0dSUlrich Drepper return sys_mkdirat(AT_FDCWD, pathname, mode); 35845590ff0dSUlrich Drepper } 35855590ff0dSUlrich Drepper 35861da177e4SLinus Torvalds /* 3587a71905f0SSage Weil * The dentry_unhash() helper will try to drop the dentry early: we 3588c0d02594SJ. Bruce Fields * should have a usage count of 1 if we're the only user of this 3589a71905f0SSage Weil * dentry, and if that is true (possibly after pruning the dcache), 3590a71905f0SSage Weil * then we drop the dentry now. 35911da177e4SLinus Torvalds * 35921da177e4SLinus Torvalds * A low-level filesystem can, if it choses, legally 35931da177e4SLinus Torvalds * do a 35941da177e4SLinus Torvalds * 35951da177e4SLinus Torvalds * if (!d_unhashed(dentry)) 35961da177e4SLinus Torvalds * return -EBUSY; 35971da177e4SLinus Torvalds * 35981da177e4SLinus Torvalds * if it cannot handle the case of removing a directory 35991da177e4SLinus Torvalds * that is still in use by something else.. 36001da177e4SLinus Torvalds */ 36011da177e4SLinus Torvalds void dentry_unhash(struct dentry *dentry) 36021da177e4SLinus Torvalds { 36031da177e4SLinus Torvalds shrink_dcache_parent(dentry); 36041da177e4SLinus Torvalds spin_lock(&dentry->d_lock); 360598474236SWaiman Long if (dentry->d_lockref.count == 1) 36061da177e4SLinus Torvalds __d_drop(dentry); 36071da177e4SLinus Torvalds spin_unlock(&dentry->d_lock); 36081da177e4SLinus Torvalds } 36094d359507SAl Viro EXPORT_SYMBOL(dentry_unhash); 36101da177e4SLinus Torvalds 36111da177e4SLinus Torvalds int vfs_rmdir(struct inode *dir, struct dentry *dentry) 36121da177e4SLinus Torvalds { 36131da177e4SLinus Torvalds int error = may_delete(dir, dentry, 1); 36141da177e4SLinus Torvalds 36151da177e4SLinus Torvalds if (error) 36161da177e4SLinus Torvalds return error; 36171da177e4SLinus Torvalds 3618acfa4380SAl Viro if (!dir->i_op->rmdir) 36191da177e4SLinus Torvalds return -EPERM; 36201da177e4SLinus Torvalds 36211d2ef590SAl Viro dget(dentry); 36221b1dcc1bSJes Sorensen mutex_lock(&dentry->d_inode->i_mutex); 3623912dbc15SSage Weil 36241da177e4SLinus Torvalds error = -EBUSY; 36257af1364fSEric W. Biederman if (is_local_mountpoint(dentry)) 3626912dbc15SSage Weil goto out; 3627912dbc15SSage Weil 36281da177e4SLinus Torvalds error = security_inode_rmdir(dir, dentry); 3629912dbc15SSage Weil if (error) 3630912dbc15SSage Weil goto out; 3631912dbc15SSage Weil 36323cebde24SSage Weil shrink_dcache_parent(dentry); 36331da177e4SLinus Torvalds error = dir->i_op->rmdir(dir, dentry); 3634912dbc15SSage Weil if (error) 3635912dbc15SSage Weil goto out; 3636912dbc15SSage Weil 36371da177e4SLinus Torvalds dentry->d_inode->i_flags |= S_DEAD; 3638d83c49f3SAl Viro dont_mount(dentry); 36398ed936b5SEric W. Biederman detach_mounts(dentry); 36401da177e4SLinus Torvalds 3641912dbc15SSage Weil out: 3642912dbc15SSage Weil mutex_unlock(&dentry->d_inode->i_mutex); 36431d2ef590SAl Viro dput(dentry); 3644912dbc15SSage Weil if (!error) 3645912dbc15SSage Weil d_delete(dentry); 36461da177e4SLinus Torvalds return error; 36471da177e4SLinus Torvalds } 36484d359507SAl Viro EXPORT_SYMBOL(vfs_rmdir); 36491da177e4SLinus Torvalds 36505590ff0dSUlrich Drepper static long do_rmdir(int dfd, const char __user *pathname) 36511da177e4SLinus Torvalds { 36521da177e4SLinus Torvalds int error = 0; 365391a27b2aSJeff Layton struct filename *name; 36541da177e4SLinus Torvalds struct dentry *dentry; 3655f5beed75SAl Viro struct path path; 3656f5beed75SAl Viro struct qstr last; 3657f5beed75SAl Viro int type; 3658c6ee9206SJeff Layton unsigned int lookup_flags = 0; 3659c6ee9206SJeff Layton retry: 3660f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3661f5beed75SAl Viro &path, &last, &type, lookup_flags); 366291a27b2aSJeff Layton if (IS_ERR(name)) 366391a27b2aSJeff Layton return PTR_ERR(name); 36641da177e4SLinus Torvalds 3665f5beed75SAl Viro switch (type) { 36661da177e4SLinus Torvalds case LAST_DOTDOT: 36671da177e4SLinus Torvalds error = -ENOTEMPTY; 36681da177e4SLinus Torvalds goto exit1; 36691da177e4SLinus Torvalds case LAST_DOT: 36701da177e4SLinus Torvalds error = -EINVAL; 36711da177e4SLinus Torvalds goto exit1; 36721da177e4SLinus Torvalds case LAST_ROOT: 36731da177e4SLinus Torvalds error = -EBUSY; 36741da177e4SLinus Torvalds goto exit1; 36751da177e4SLinus Torvalds } 36760612d9fbSOGAWA Hirofumi 3677f5beed75SAl Viro error = mnt_want_write(path.mnt); 3678c30dabfeSJan Kara if (error) 3679c30dabfeSJan Kara goto exit1; 36800612d9fbSOGAWA Hirofumi 3681f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3682f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 36831da177e4SLinus Torvalds error = PTR_ERR(dentry); 36846902d925SDave Hansen if (IS_ERR(dentry)) 36856902d925SDave Hansen goto exit2; 3686e6bc45d6STheodore Ts'o if (!dentry->d_inode) { 3687e6bc45d6STheodore Ts'o error = -ENOENT; 3688e6bc45d6STheodore Ts'o goto exit3; 3689e6bc45d6STheodore Ts'o } 3690f5beed75SAl Viro error = security_path_rmdir(&path, dentry); 3691be6d3e56SKentaro Takeda if (error) 3692c30dabfeSJan Kara goto exit3; 3693f5beed75SAl Viro error = vfs_rmdir(path.dentry->d_inode, dentry); 36940622753bSDave Hansen exit3: 36951da177e4SLinus Torvalds dput(dentry); 36966902d925SDave Hansen exit2: 3697f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 3698f5beed75SAl Viro mnt_drop_write(path.mnt); 36991da177e4SLinus Torvalds exit1: 3700f5beed75SAl Viro path_put(&path); 37011da177e4SLinus Torvalds putname(name); 3702c6ee9206SJeff Layton if (retry_estale(error, lookup_flags)) { 3703c6ee9206SJeff Layton lookup_flags |= LOOKUP_REVAL; 3704c6ee9206SJeff Layton goto retry; 3705c6ee9206SJeff Layton } 37061da177e4SLinus Torvalds return error; 37071da177e4SLinus Torvalds } 37081da177e4SLinus Torvalds 37093cdad428SHeiko Carstens SYSCALL_DEFINE1(rmdir, const char __user *, pathname) 37105590ff0dSUlrich Drepper { 37115590ff0dSUlrich Drepper return do_rmdir(AT_FDCWD, pathname); 37125590ff0dSUlrich Drepper } 37135590ff0dSUlrich Drepper 3714b21996e3SJ. Bruce Fields /** 3715b21996e3SJ. Bruce Fields * vfs_unlink - unlink a filesystem object 3716b21996e3SJ. Bruce Fields * @dir: parent directory 3717b21996e3SJ. Bruce Fields * @dentry: victim 3718b21996e3SJ. Bruce Fields * @delegated_inode: returns victim inode, if the inode is delegated. 3719b21996e3SJ. Bruce Fields * 3720b21996e3SJ. Bruce Fields * The caller must hold dir->i_mutex. 3721b21996e3SJ. Bruce Fields * 3722b21996e3SJ. Bruce Fields * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and 3723b21996e3SJ. Bruce Fields * return a reference to the inode in delegated_inode. The caller 3724b21996e3SJ. Bruce Fields * should then break the delegation on that inode and retry. Because 3725b21996e3SJ. Bruce Fields * breaking a delegation may take a long time, the caller should drop 3726b21996e3SJ. Bruce Fields * dir->i_mutex before doing so. 3727b21996e3SJ. Bruce Fields * 3728b21996e3SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3729b21996e3SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3730b21996e3SJ. Bruce Fields * to be NFS exported. 3731b21996e3SJ. Bruce Fields */ 3732b21996e3SJ. Bruce Fields int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode) 37331da177e4SLinus Torvalds { 37349accbb97SJ. Bruce Fields struct inode *target = dentry->d_inode; 37351da177e4SLinus Torvalds int error = may_delete(dir, dentry, 0); 37361da177e4SLinus Torvalds 37371da177e4SLinus Torvalds if (error) 37381da177e4SLinus Torvalds return error; 37391da177e4SLinus Torvalds 3740acfa4380SAl Viro if (!dir->i_op->unlink) 37411da177e4SLinus Torvalds return -EPERM; 37421da177e4SLinus Torvalds 37439accbb97SJ. Bruce Fields mutex_lock(&target->i_mutex); 37448ed936b5SEric W. Biederman if (is_local_mountpoint(dentry)) 37451da177e4SLinus Torvalds error = -EBUSY; 37461da177e4SLinus Torvalds else { 37471da177e4SLinus Torvalds error = security_inode_unlink(dir, dentry); 3748bec1052eSAl Viro if (!error) { 37495a14696cSJ. Bruce Fields error = try_break_deleg(target, delegated_inode); 37505a14696cSJ. Bruce Fields if (error) 3751b21996e3SJ. Bruce Fields goto out; 37521da177e4SLinus Torvalds error = dir->i_op->unlink(dir, dentry); 37538ed936b5SEric W. Biederman if (!error) { 3754d83c49f3SAl Viro dont_mount(dentry); 37558ed936b5SEric W. Biederman detach_mounts(dentry); 37568ed936b5SEric W. Biederman } 3757bec1052eSAl Viro } 37581da177e4SLinus Torvalds } 3759b21996e3SJ. Bruce Fields out: 37609accbb97SJ. Bruce Fields mutex_unlock(&target->i_mutex); 37611da177e4SLinus Torvalds 37621da177e4SLinus Torvalds /* We don't d_delete() NFS sillyrenamed files--they still exist. */ 37631da177e4SLinus Torvalds if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) { 37649accbb97SJ. Bruce Fields fsnotify_link_count(target); 37651da177e4SLinus Torvalds d_delete(dentry); 37661da177e4SLinus Torvalds } 37670eeca283SRobert Love 37681da177e4SLinus Torvalds return error; 37691da177e4SLinus Torvalds } 37704d359507SAl Viro EXPORT_SYMBOL(vfs_unlink); 37711da177e4SLinus Torvalds 37721da177e4SLinus Torvalds /* 37731da177e4SLinus Torvalds * Make sure that the actual truncation of the file will occur outside its 37741b1dcc1bSJes Sorensen * directory's i_mutex. Truncate can take a long time if there is a lot of 37751da177e4SLinus Torvalds * writeout happening, and we don't want to prevent access to the directory 37761da177e4SLinus Torvalds * while waiting on the I/O. 37771da177e4SLinus Torvalds */ 37785590ff0dSUlrich Drepper static long do_unlinkat(int dfd, const char __user *pathname) 37791da177e4SLinus Torvalds { 37802ad94ae6SAl Viro int error; 378191a27b2aSJeff Layton struct filename *name; 37821da177e4SLinus Torvalds struct dentry *dentry; 3783f5beed75SAl Viro struct path path; 3784f5beed75SAl Viro struct qstr last; 3785f5beed75SAl Viro int type; 37861da177e4SLinus Torvalds struct inode *inode = NULL; 3787b21996e3SJ. Bruce Fields struct inode *delegated_inode = NULL; 37885d18f813SJeff Layton unsigned int lookup_flags = 0; 37895d18f813SJeff Layton retry: 3790f5beed75SAl Viro name = user_path_parent(dfd, pathname, 3791f5beed75SAl Viro &path, &last, &type, lookup_flags); 379291a27b2aSJeff Layton if (IS_ERR(name)) 379391a27b2aSJeff Layton return PTR_ERR(name); 37942ad94ae6SAl Viro 37951da177e4SLinus Torvalds error = -EISDIR; 3796f5beed75SAl Viro if (type != LAST_NORM) 37971da177e4SLinus Torvalds goto exit1; 37980612d9fbSOGAWA Hirofumi 3799f5beed75SAl Viro error = mnt_want_write(path.mnt); 3800c30dabfeSJan Kara if (error) 3801c30dabfeSJan Kara goto exit1; 3802b21996e3SJ. Bruce Fields retry_deleg: 3803f5beed75SAl Viro mutex_lock_nested(&path.dentry->d_inode->i_mutex, I_MUTEX_PARENT); 3804f5beed75SAl Viro dentry = __lookup_hash(&last, path.dentry, lookup_flags); 38051da177e4SLinus Torvalds error = PTR_ERR(dentry); 38061da177e4SLinus Torvalds if (!IS_ERR(dentry)) { 38071da177e4SLinus Torvalds /* Why not before? Because we want correct error value */ 3808f5beed75SAl Viro if (last.name[last.len]) 380950338b88STörök Edwin goto slashes; 38101da177e4SLinus Torvalds inode = dentry->d_inode; 3811b18825a7SDavid Howells if (d_is_negative(dentry)) 3812e6bc45d6STheodore Ts'o goto slashes; 38137de9c6eeSAl Viro ihold(inode); 3814f5beed75SAl Viro error = security_path_unlink(&path, dentry); 3815be6d3e56SKentaro Takeda if (error) 3816c30dabfeSJan Kara goto exit2; 3817f5beed75SAl Viro error = vfs_unlink(path.dentry->d_inode, dentry, &delegated_inode); 38181da177e4SLinus Torvalds exit2: 38191da177e4SLinus Torvalds dput(dentry); 38201da177e4SLinus Torvalds } 3821f5beed75SAl Viro mutex_unlock(&path.dentry->d_inode->i_mutex); 38221da177e4SLinus Torvalds if (inode) 38231da177e4SLinus Torvalds iput(inode); /* truncate the inode here */ 3824b21996e3SJ. Bruce Fields inode = NULL; 3825b21996e3SJ. Bruce Fields if (delegated_inode) { 38265a14696cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 3827b21996e3SJ. Bruce Fields if (!error) 3828b21996e3SJ. Bruce Fields goto retry_deleg; 3829b21996e3SJ. Bruce Fields } 3830f5beed75SAl Viro mnt_drop_write(path.mnt); 38311da177e4SLinus Torvalds exit1: 3832f5beed75SAl Viro path_put(&path); 38331da177e4SLinus Torvalds putname(name); 38345d18f813SJeff Layton if (retry_estale(error, lookup_flags)) { 38355d18f813SJeff Layton lookup_flags |= LOOKUP_REVAL; 38365d18f813SJeff Layton inode = NULL; 38375d18f813SJeff Layton goto retry; 38385d18f813SJeff Layton } 38391da177e4SLinus Torvalds return error; 38401da177e4SLinus Torvalds 38411da177e4SLinus Torvalds slashes: 3842b18825a7SDavid Howells if (d_is_negative(dentry)) 3843b18825a7SDavid Howells error = -ENOENT; 384444b1d530SMiklos Szeredi else if (d_is_dir(dentry)) 3845b18825a7SDavid Howells error = -EISDIR; 3846b18825a7SDavid Howells else 3847b18825a7SDavid Howells error = -ENOTDIR; 38481da177e4SLinus Torvalds goto exit2; 38491da177e4SLinus Torvalds } 38501da177e4SLinus Torvalds 38512e4d0924SHeiko Carstens SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) 38525590ff0dSUlrich Drepper { 38535590ff0dSUlrich Drepper if ((flag & ~AT_REMOVEDIR) != 0) 38545590ff0dSUlrich Drepper return -EINVAL; 38555590ff0dSUlrich Drepper 38565590ff0dSUlrich Drepper if (flag & AT_REMOVEDIR) 38575590ff0dSUlrich Drepper return do_rmdir(dfd, pathname); 38585590ff0dSUlrich Drepper 38595590ff0dSUlrich Drepper return do_unlinkat(dfd, pathname); 38605590ff0dSUlrich Drepper } 38615590ff0dSUlrich Drepper 38623480b257SHeiko Carstens SYSCALL_DEFINE1(unlink, const char __user *, pathname) 38635590ff0dSUlrich Drepper { 38645590ff0dSUlrich Drepper return do_unlinkat(AT_FDCWD, pathname); 38655590ff0dSUlrich Drepper } 38665590ff0dSUlrich Drepper 3867db2e747bSMiklos Szeredi int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname) 38681da177e4SLinus Torvalds { 3869a95164d9SMiklos Szeredi int error = may_create(dir, dentry); 38701da177e4SLinus Torvalds 38711da177e4SLinus Torvalds if (error) 38721da177e4SLinus Torvalds return error; 38731da177e4SLinus Torvalds 3874acfa4380SAl Viro if (!dir->i_op->symlink) 38751da177e4SLinus Torvalds return -EPERM; 38761da177e4SLinus Torvalds 38771da177e4SLinus Torvalds error = security_inode_symlink(dir, dentry, oldname); 38781da177e4SLinus Torvalds if (error) 38791da177e4SLinus Torvalds return error; 38801da177e4SLinus Torvalds 38811da177e4SLinus Torvalds error = dir->i_op->symlink(dir, dentry, oldname); 3882a74574aaSStephen Smalley if (!error) 3883f38aa942SAmy Griffis fsnotify_create(dir, dentry); 38841da177e4SLinus Torvalds return error; 38851da177e4SLinus Torvalds } 38864d359507SAl Viro EXPORT_SYMBOL(vfs_symlink); 38871da177e4SLinus Torvalds 38882e4d0924SHeiko Carstens SYSCALL_DEFINE3(symlinkat, const char __user *, oldname, 38892e4d0924SHeiko Carstens int, newdfd, const char __user *, newname) 38901da177e4SLinus Torvalds { 38912ad94ae6SAl Viro int error; 389291a27b2aSJeff Layton struct filename *from; 38936902d925SDave Hansen struct dentry *dentry; 3894dae6ad8fSAl Viro struct path path; 3895f46d3567SJeff Layton unsigned int lookup_flags = 0; 38961da177e4SLinus Torvalds 38971da177e4SLinus Torvalds from = getname(oldname); 38981da177e4SLinus Torvalds if (IS_ERR(from)) 38991da177e4SLinus Torvalds return PTR_ERR(from); 3900f46d3567SJeff Layton retry: 3901f46d3567SJeff Layton dentry = user_path_create(newdfd, newname, &path, lookup_flags); 39021da177e4SLinus Torvalds error = PTR_ERR(dentry); 39036902d925SDave Hansen if (IS_ERR(dentry)) 3904dae6ad8fSAl Viro goto out_putname; 39056902d925SDave Hansen 390691a27b2aSJeff Layton error = security_path_symlink(&path, dentry, from->name); 3907a8104a9fSAl Viro if (!error) 390891a27b2aSJeff Layton error = vfs_symlink(path.dentry->d_inode, dentry, from->name); 3909921a1650SAl Viro done_path_create(&path, dentry); 3910f46d3567SJeff Layton if (retry_estale(error, lookup_flags)) { 3911f46d3567SJeff Layton lookup_flags |= LOOKUP_REVAL; 3912f46d3567SJeff Layton goto retry; 3913f46d3567SJeff Layton } 39146902d925SDave Hansen out_putname: 39151da177e4SLinus Torvalds putname(from); 39161da177e4SLinus Torvalds return error; 39171da177e4SLinus Torvalds } 39181da177e4SLinus Torvalds 39193480b257SHeiko Carstens SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname) 39205590ff0dSUlrich Drepper { 39215590ff0dSUlrich Drepper return sys_symlinkat(oldname, AT_FDCWD, newname); 39225590ff0dSUlrich Drepper } 39235590ff0dSUlrich Drepper 3924146a8595SJ. Bruce Fields /** 3925146a8595SJ. Bruce Fields * vfs_link - create a new link 3926146a8595SJ. Bruce Fields * @old_dentry: object to be linked 3927146a8595SJ. Bruce Fields * @dir: new parent 3928146a8595SJ. Bruce Fields * @new_dentry: where to create the new link 3929146a8595SJ. Bruce Fields * @delegated_inode: returns inode needing a delegation break 3930146a8595SJ. Bruce Fields * 3931146a8595SJ. Bruce Fields * The caller must hold dir->i_mutex 3932146a8595SJ. Bruce Fields * 3933146a8595SJ. Bruce Fields * If vfs_link discovers a delegation on the to-be-linked file in need 3934146a8595SJ. Bruce Fields * of breaking, it will return -EWOULDBLOCK and return a reference to the 3935146a8595SJ. Bruce Fields * inode in delegated_inode. The caller should then break the delegation 3936146a8595SJ. Bruce Fields * and retry. Because breaking a delegation may take a long time, the 3937146a8595SJ. Bruce Fields * caller should drop the i_mutex before doing so. 3938146a8595SJ. Bruce Fields * 3939146a8595SJ. Bruce Fields * Alternatively, a caller may pass NULL for delegated_inode. This may 3940146a8595SJ. Bruce Fields * be appropriate for callers that expect the underlying filesystem not 3941146a8595SJ. Bruce Fields * to be NFS exported. 3942146a8595SJ. Bruce Fields */ 3943146a8595SJ. Bruce Fields int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode) 39441da177e4SLinus Torvalds { 39451da177e4SLinus Torvalds struct inode *inode = old_dentry->d_inode; 39468de52778SAl Viro unsigned max_links = dir->i_sb->s_max_links; 39471da177e4SLinus Torvalds int error; 39481da177e4SLinus Torvalds 39491da177e4SLinus Torvalds if (!inode) 39501da177e4SLinus Torvalds return -ENOENT; 39511da177e4SLinus Torvalds 3952a95164d9SMiklos Szeredi error = may_create(dir, new_dentry); 39531da177e4SLinus Torvalds if (error) 39541da177e4SLinus Torvalds return error; 39551da177e4SLinus Torvalds 39561da177e4SLinus Torvalds if (dir->i_sb != inode->i_sb) 39571da177e4SLinus Torvalds return -EXDEV; 39581da177e4SLinus Torvalds 39591da177e4SLinus Torvalds /* 39601da177e4SLinus Torvalds * A link to an append-only or immutable file cannot be created. 39611da177e4SLinus Torvalds */ 39621da177e4SLinus Torvalds if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 39631da177e4SLinus Torvalds return -EPERM; 3964acfa4380SAl Viro if (!dir->i_op->link) 39651da177e4SLinus Torvalds return -EPERM; 39667e79eedbSTetsuo Handa if (S_ISDIR(inode->i_mode)) 39671da177e4SLinus Torvalds return -EPERM; 39681da177e4SLinus Torvalds 39691da177e4SLinus Torvalds error = security_inode_link(old_dentry, dir, new_dentry); 39701da177e4SLinus Torvalds if (error) 39711da177e4SLinus Torvalds return error; 39721da177e4SLinus Torvalds 39737e79eedbSTetsuo Handa mutex_lock(&inode->i_mutex); 3974aae8a97dSAneesh Kumar K.V /* Make sure we don't allow creating hardlink to an unlinked file */ 3975f4e0c30cSAl Viro if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE)) 3976aae8a97dSAneesh Kumar K.V error = -ENOENT; 39778de52778SAl Viro else if (max_links && inode->i_nlink >= max_links) 39788de52778SAl Viro error = -EMLINK; 3979146a8595SJ. Bruce Fields else { 3980146a8595SJ. Bruce Fields error = try_break_deleg(inode, delegated_inode); 3981146a8595SJ. Bruce Fields if (!error) 39821da177e4SLinus Torvalds error = dir->i_op->link(old_dentry, dir, new_dentry); 3983146a8595SJ. Bruce Fields } 3984f4e0c30cSAl Viro 3985f4e0c30cSAl Viro if (!error && (inode->i_state & I_LINKABLE)) { 3986f4e0c30cSAl Viro spin_lock(&inode->i_lock); 3987f4e0c30cSAl Viro inode->i_state &= ~I_LINKABLE; 3988f4e0c30cSAl Viro spin_unlock(&inode->i_lock); 3989f4e0c30cSAl Viro } 39907e79eedbSTetsuo Handa mutex_unlock(&inode->i_mutex); 3991e31e14ecSStephen Smalley if (!error) 39927e79eedbSTetsuo Handa fsnotify_link(dir, inode, new_dentry); 39931da177e4SLinus Torvalds return error; 39941da177e4SLinus Torvalds } 39954d359507SAl Viro EXPORT_SYMBOL(vfs_link); 39961da177e4SLinus Torvalds 39971da177e4SLinus Torvalds /* 39981da177e4SLinus Torvalds * Hardlinks are often used in delicate situations. We avoid 39991da177e4SLinus Torvalds * security-related surprises by not following symlinks on the 40001da177e4SLinus Torvalds * newname. --KAB 40011da177e4SLinus Torvalds * 40021da177e4SLinus Torvalds * We don't follow them on the oldname either to be compatible 40031da177e4SLinus Torvalds * with linux 2.0, and to avoid hard-linking to directories 40041da177e4SLinus Torvalds * and other special files. --ADM 40051da177e4SLinus Torvalds */ 40062e4d0924SHeiko Carstens SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname, 40072e4d0924SHeiko Carstens int, newdfd, const char __user *, newname, int, flags) 40081da177e4SLinus Torvalds { 40091da177e4SLinus Torvalds struct dentry *new_dentry; 4010dae6ad8fSAl Viro struct path old_path, new_path; 4011146a8595SJ. Bruce Fields struct inode *delegated_inode = NULL; 401211a7b371SAneesh Kumar K.V int how = 0; 40131da177e4SLinus Torvalds int error; 40141da177e4SLinus Torvalds 401511a7b371SAneesh Kumar K.V if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) 4016c04030e1SUlrich Drepper return -EINVAL; 401711a7b371SAneesh Kumar K.V /* 4018f0cc6ffbSLinus Torvalds * To use null names we require CAP_DAC_READ_SEARCH 4019f0cc6ffbSLinus Torvalds * This ensures that not everyone will be able to create 4020f0cc6ffbSLinus Torvalds * handlink using the passed filedescriptor. 402111a7b371SAneesh Kumar K.V */ 4022f0cc6ffbSLinus Torvalds if (flags & AT_EMPTY_PATH) { 4023f0cc6ffbSLinus Torvalds if (!capable(CAP_DAC_READ_SEARCH)) 4024f0cc6ffbSLinus Torvalds return -ENOENT; 402511a7b371SAneesh Kumar K.V how = LOOKUP_EMPTY; 4026f0cc6ffbSLinus Torvalds } 4027c04030e1SUlrich Drepper 402811a7b371SAneesh Kumar K.V if (flags & AT_SYMLINK_FOLLOW) 402911a7b371SAneesh Kumar K.V how |= LOOKUP_FOLLOW; 4030442e31caSJeff Layton retry: 403111a7b371SAneesh Kumar K.V error = user_path_at(olddfd, oldname, how, &old_path); 40321da177e4SLinus Torvalds if (error) 40332ad94ae6SAl Viro return error; 40342ad94ae6SAl Viro 4035442e31caSJeff Layton new_dentry = user_path_create(newdfd, newname, &new_path, 4036442e31caSJeff Layton (how & LOOKUP_REVAL)); 40371da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 40386902d925SDave Hansen if (IS_ERR(new_dentry)) 4039dae6ad8fSAl Viro goto out; 4040dae6ad8fSAl Viro 4041dae6ad8fSAl Viro error = -EXDEV; 4042dae6ad8fSAl Viro if (old_path.mnt != new_path.mnt) 4043dae6ad8fSAl Viro goto out_dput; 4044800179c9SKees Cook error = may_linkat(&old_path); 4045800179c9SKees Cook if (unlikely(error)) 4046800179c9SKees Cook goto out_dput; 4047dae6ad8fSAl Viro error = security_path_link(old_path.dentry, &new_path, new_dentry); 4048be6d3e56SKentaro Takeda if (error) 4049a8104a9fSAl Viro goto out_dput; 4050146a8595SJ. Bruce Fields error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode); 405175c3f29dSDave Hansen out_dput: 4052921a1650SAl Viro done_path_create(&new_path, new_dentry); 4053146a8595SJ. Bruce Fields if (delegated_inode) { 4054146a8595SJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 4055d22e6338SOleg Drokin if (!error) { 4056d22e6338SOleg Drokin path_put(&old_path); 4057146a8595SJ. Bruce Fields goto retry; 4058146a8595SJ. Bruce Fields } 4059d22e6338SOleg Drokin } 4060442e31caSJeff Layton if (retry_estale(error, how)) { 4061d22e6338SOleg Drokin path_put(&old_path); 4062442e31caSJeff Layton how |= LOOKUP_REVAL; 4063442e31caSJeff Layton goto retry; 4064442e31caSJeff Layton } 40651da177e4SLinus Torvalds out: 40662d8f3038SAl Viro path_put(&old_path); 40671da177e4SLinus Torvalds 40681da177e4SLinus Torvalds return error; 40691da177e4SLinus Torvalds } 40701da177e4SLinus Torvalds 40713480b257SHeiko Carstens SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname) 40725590ff0dSUlrich Drepper { 4073c04030e1SUlrich Drepper return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 40745590ff0dSUlrich Drepper } 40755590ff0dSUlrich Drepper 4076bc27027aSMiklos Szeredi /** 4077bc27027aSMiklos Szeredi * vfs_rename - rename a filesystem object 4078bc27027aSMiklos Szeredi * @old_dir: parent of source 4079bc27027aSMiklos Szeredi * @old_dentry: source 4080bc27027aSMiklos Szeredi * @new_dir: parent of destination 4081bc27027aSMiklos Szeredi * @new_dentry: destination 4082bc27027aSMiklos Szeredi * @delegated_inode: returns an inode needing a delegation break 4083520c8b16SMiklos Szeredi * @flags: rename flags 4084bc27027aSMiklos Szeredi * 4085bc27027aSMiklos Szeredi * The caller must hold multiple mutexes--see lock_rename()). 4086bc27027aSMiklos Szeredi * 4087bc27027aSMiklos Szeredi * If vfs_rename discovers a delegation in need of breaking at either 4088bc27027aSMiklos Szeredi * the source or destination, it will return -EWOULDBLOCK and return a 4089bc27027aSMiklos Szeredi * reference to the inode in delegated_inode. The caller should then 4090bc27027aSMiklos Szeredi * break the delegation and retry. Because breaking a delegation may 4091bc27027aSMiklos Szeredi * take a long time, the caller should drop all locks before doing 4092bc27027aSMiklos Szeredi * so. 4093bc27027aSMiklos Szeredi * 4094bc27027aSMiklos Szeredi * Alternatively, a caller may pass NULL for delegated_inode. This may 4095bc27027aSMiklos Szeredi * be appropriate for callers that expect the underlying filesystem not 4096bc27027aSMiklos Szeredi * to be NFS exported. 4097bc27027aSMiklos Szeredi * 40981da177e4SLinus Torvalds * The worst of all namespace operations - renaming directory. "Perverted" 40991da177e4SLinus Torvalds * doesn't even start to describe it. Somebody in UCB had a heck of a trip... 41001da177e4SLinus Torvalds * Problems: 4101d03b29a2SJ. Bruce Fields * a) we can get into loop creation. 41021da177e4SLinus Torvalds * b) race potential - two innocent renames can create a loop together. 41031da177e4SLinus Torvalds * That's where 4.4 screws up. Current fix: serialization on 4104a11f3a05SArjan van de Ven * sb->s_vfs_rename_mutex. We might be more accurate, but that's another 41051da177e4SLinus Torvalds * story. 41066cedba89SJ. Bruce Fields * c) we have to lock _four_ objects - parents and victim (if it exists), 41076cedba89SJ. Bruce Fields * and source (if it is not a directory). 41081b1dcc1bSJes Sorensen * And that - after we got ->i_mutex on parents (until then we don't know 41091da177e4SLinus Torvalds * whether the target exists). Solution: try to be smart with locking 41101da177e4SLinus Torvalds * order for inodes. We rely on the fact that tree topology may change 4111a11f3a05SArjan van de Ven * only under ->s_vfs_rename_mutex _and_ that parent of the object we 41121da177e4SLinus Torvalds * move will be locked. Thus we can rank directories by the tree 41131da177e4SLinus Torvalds * (ancestors first) and rank all non-directories after them. 41141da177e4SLinus Torvalds * That works since everybody except rename does "lock parent, lookup, 4115a11f3a05SArjan van de Ven * lock child" and rename is under ->s_vfs_rename_mutex. 41161da177e4SLinus Torvalds * HOWEVER, it relies on the assumption that any object with ->lookup() 41171da177e4SLinus Torvalds * has no more than 1 dentry. If "hybrid" objects will ever appear, 41181da177e4SLinus Torvalds * we'd better make sure that there's no link(2) for them. 4119e4eaac06SSage Weil * d) conversion from fhandle to dentry may come in the wrong moment - when 41201b1dcc1bSJes Sorensen * we are removing the target. Solution: we will have to grab ->i_mutex 41211da177e4SLinus Torvalds * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on 4122c41b20e7SAdam Buchbinder * ->i_mutex on parents, which works but leads to some truly excessive 41231da177e4SLinus Torvalds * locking]. 41241da177e4SLinus Torvalds */ 41251da177e4SLinus Torvalds int vfs_rename(struct inode *old_dir, struct dentry *old_dentry, 41268e6d782cSJ. Bruce Fields struct inode *new_dir, struct dentry *new_dentry, 4127520c8b16SMiklos Szeredi struct inode **delegated_inode, unsigned int flags) 41281da177e4SLinus Torvalds { 41291da177e4SLinus Torvalds int error; 4130bc27027aSMiklos Szeredi bool is_dir = d_is_dir(old_dentry); 413159b0df21SEric Paris const unsigned char *old_name; 4132bc27027aSMiklos Szeredi struct inode *source = old_dentry->d_inode; 4133bc27027aSMiklos Szeredi struct inode *target = new_dentry->d_inode; 4134da1ce067SMiklos Szeredi bool new_is_dir = false; 4135da1ce067SMiklos Szeredi unsigned max_links = new_dir->i_sb->s_max_links; 41361da177e4SLinus Torvalds 4137bc27027aSMiklos Szeredi if (source == target) 41381da177e4SLinus Torvalds return 0; 41391da177e4SLinus Torvalds 41401da177e4SLinus Torvalds error = may_delete(old_dir, old_dentry, is_dir); 41411da177e4SLinus Torvalds if (error) 41421da177e4SLinus Torvalds return error; 41431da177e4SLinus Torvalds 4144da1ce067SMiklos Szeredi if (!target) { 4145a95164d9SMiklos Szeredi error = may_create(new_dir, new_dentry); 4146da1ce067SMiklos Szeredi } else { 4147da1ce067SMiklos Szeredi new_is_dir = d_is_dir(new_dentry); 4148da1ce067SMiklos Szeredi 4149da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 41501da177e4SLinus Torvalds error = may_delete(new_dir, new_dentry, is_dir); 4151da1ce067SMiklos Szeredi else 4152da1ce067SMiklos Szeredi error = may_delete(new_dir, new_dentry, new_is_dir); 4153da1ce067SMiklos Szeredi } 41541da177e4SLinus Torvalds if (error) 41551da177e4SLinus Torvalds return error; 41561da177e4SLinus Torvalds 41577177a9c4SMiklos Szeredi if (!old_dir->i_op->rename && !old_dir->i_op->rename2) 41581da177e4SLinus Torvalds return -EPERM; 41591da177e4SLinus Torvalds 4160520c8b16SMiklos Szeredi if (flags && !old_dir->i_op->rename2) 4161520c8b16SMiklos Szeredi return -EINVAL; 4162520c8b16SMiklos Szeredi 4163bc27027aSMiklos Szeredi /* 4164bc27027aSMiklos Szeredi * If we are going to change the parent - check write permissions, 4165bc27027aSMiklos Szeredi * we'll need to flip '..'. 4166bc27027aSMiklos Szeredi */ 4167da1ce067SMiklos Szeredi if (new_dir != old_dir) { 4168da1ce067SMiklos Szeredi if (is_dir) { 4169bc27027aSMiklos Szeredi error = inode_permission(source, MAY_WRITE); 4170bc27027aSMiklos Szeredi if (error) 4171bc27027aSMiklos Szeredi return error; 4172bc27027aSMiklos Szeredi } 4173da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && new_is_dir) { 4174da1ce067SMiklos Szeredi error = inode_permission(target, MAY_WRITE); 4175da1ce067SMiklos Szeredi if (error) 4176da1ce067SMiklos Szeredi return error; 4177da1ce067SMiklos Szeredi } 4178da1ce067SMiklos Szeredi } 41790eeca283SRobert Love 41800b3974ebSMiklos Szeredi error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry, 41810b3974ebSMiklos Szeredi flags); 4182bc27027aSMiklos Szeredi if (error) 4183bc27027aSMiklos Szeredi return error; 4184bc27027aSMiklos Szeredi 4185bc27027aSMiklos Szeredi old_name = fsnotify_oldname_init(old_dentry->d_name.name); 4186bc27027aSMiklos Szeredi dget(new_dentry); 4187da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4188bc27027aSMiklos Szeredi lock_two_nondirectories(source, target); 4189bc27027aSMiklos Szeredi else if (target) 4190bc27027aSMiklos Szeredi mutex_lock(&target->i_mutex); 4191bc27027aSMiklos Szeredi 4192bc27027aSMiklos Szeredi error = -EBUSY; 41937af1364fSEric W. Biederman if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry)) 4194bc27027aSMiklos Szeredi goto out; 4195bc27027aSMiklos Szeredi 4196da1ce067SMiklos Szeredi if (max_links && new_dir != old_dir) { 4197bc27027aSMiklos Szeredi error = -EMLINK; 4198da1ce067SMiklos Szeredi if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links) 4199bc27027aSMiklos Szeredi goto out; 4200da1ce067SMiklos Szeredi if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir && 4201da1ce067SMiklos Szeredi old_dir->i_nlink >= max_links) 4202da1ce067SMiklos Szeredi goto out; 4203da1ce067SMiklos Szeredi } 4204da1ce067SMiklos Szeredi if (is_dir && !(flags & RENAME_EXCHANGE) && target) 4205bc27027aSMiklos Szeredi shrink_dcache_parent(new_dentry); 4206da1ce067SMiklos Szeredi if (!is_dir) { 4207bc27027aSMiklos Szeredi error = try_break_deleg(source, delegated_inode); 4208bc27027aSMiklos Szeredi if (error) 4209bc27027aSMiklos Szeredi goto out; 4210da1ce067SMiklos Szeredi } 4211da1ce067SMiklos Szeredi if (target && !new_is_dir) { 4212bc27027aSMiklos Szeredi error = try_break_deleg(target, delegated_inode); 4213bc27027aSMiklos Szeredi if (error) 4214bc27027aSMiklos Szeredi goto out; 4215bc27027aSMiklos Szeredi } 42167177a9c4SMiklos Szeredi if (!old_dir->i_op->rename2) { 4217520c8b16SMiklos Szeredi error = old_dir->i_op->rename(old_dir, old_dentry, 4218520c8b16SMiklos Szeredi new_dir, new_dentry); 4219520c8b16SMiklos Szeredi } else { 42207177a9c4SMiklos Szeredi WARN_ON(old_dir->i_op->rename != NULL); 4221520c8b16SMiklos Szeredi error = old_dir->i_op->rename2(old_dir, old_dentry, 4222520c8b16SMiklos Szeredi new_dir, new_dentry, flags); 4223520c8b16SMiklos Szeredi } 4224bc27027aSMiklos Szeredi if (error) 4225bc27027aSMiklos Szeredi goto out; 4226bc27027aSMiklos Szeredi 4227da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE) && target) { 42281da177e4SLinus Torvalds if (is_dir) 4229bc27027aSMiklos Szeredi target->i_flags |= S_DEAD; 4230bc27027aSMiklos Szeredi dont_mount(new_dentry); 42318ed936b5SEric W. Biederman detach_mounts(new_dentry); 4232bc27027aSMiklos Szeredi } 4233da1ce067SMiklos Szeredi if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) { 4234da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 4235bc27027aSMiklos Szeredi d_move(old_dentry, new_dentry); 4236da1ce067SMiklos Szeredi else 4237da1ce067SMiklos Szeredi d_exchange(old_dentry, new_dentry); 4238da1ce067SMiklos Szeredi } 4239bc27027aSMiklos Szeredi out: 4240da1ce067SMiklos Szeredi if (!is_dir || (flags & RENAME_EXCHANGE)) 4241bc27027aSMiklos Szeredi unlock_two_nondirectories(source, target); 4242bc27027aSMiklos Szeredi else if (target) 4243bc27027aSMiklos Szeredi mutex_unlock(&target->i_mutex); 4244bc27027aSMiklos Szeredi dput(new_dentry); 4245da1ce067SMiklos Szeredi if (!error) { 4246123df294SAl Viro fsnotify_move(old_dir, new_dir, old_name, is_dir, 4247da1ce067SMiklos Szeredi !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry); 4248da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4249da1ce067SMiklos Szeredi fsnotify_move(new_dir, old_dir, old_dentry->d_name.name, 4250da1ce067SMiklos Szeredi new_is_dir, NULL, new_dentry); 4251da1ce067SMiklos Szeredi } 4252da1ce067SMiklos Szeredi } 42530eeca283SRobert Love fsnotify_oldname_free(old_name); 42540eeca283SRobert Love 42551da177e4SLinus Torvalds return error; 42561da177e4SLinus Torvalds } 42574d359507SAl Viro EXPORT_SYMBOL(vfs_rename); 42581da177e4SLinus Torvalds 4259520c8b16SMiklos Szeredi SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname, 4260520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname, unsigned int, flags) 42611da177e4SLinus Torvalds { 42621da177e4SLinus Torvalds struct dentry *old_dentry, *new_dentry; 42631da177e4SLinus Torvalds struct dentry *trap; 4264f5beed75SAl Viro struct path old_path, new_path; 4265f5beed75SAl Viro struct qstr old_last, new_last; 4266f5beed75SAl Viro int old_type, new_type; 42678e6d782cSJ. Bruce Fields struct inode *delegated_inode = NULL; 426891a27b2aSJeff Layton struct filename *from; 426991a27b2aSJeff Layton struct filename *to; 4270f5beed75SAl Viro unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; 4271c6a94284SJeff Layton bool should_retry = false; 42722ad94ae6SAl Viro int error; 4273520c8b16SMiklos Szeredi 42740d7a8555SMiklos Szeredi if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) 4275da1ce067SMiklos Szeredi return -EINVAL; 4276da1ce067SMiklos Szeredi 42770d7a8555SMiklos Szeredi if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && 42780d7a8555SMiklos Szeredi (flags & RENAME_EXCHANGE)) 4279520c8b16SMiklos Szeredi return -EINVAL; 4280520c8b16SMiklos Szeredi 42810d7a8555SMiklos Szeredi if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD)) 42820d7a8555SMiklos Szeredi return -EPERM; 42830d7a8555SMiklos Szeredi 4284f5beed75SAl Viro if (flags & RENAME_EXCHANGE) 4285f5beed75SAl Viro target_flags = 0; 4286f5beed75SAl Viro 4287c6a94284SJeff Layton retry: 4288f5beed75SAl Viro from = user_path_parent(olddfd, oldname, 4289f5beed75SAl Viro &old_path, &old_last, &old_type, lookup_flags); 429091a27b2aSJeff Layton if (IS_ERR(from)) { 429191a27b2aSJeff Layton error = PTR_ERR(from); 42921da177e4SLinus Torvalds goto exit; 429391a27b2aSJeff Layton } 42941da177e4SLinus Torvalds 4295f5beed75SAl Viro to = user_path_parent(newdfd, newname, 4296f5beed75SAl Viro &new_path, &new_last, &new_type, lookup_flags); 429791a27b2aSJeff Layton if (IS_ERR(to)) { 429891a27b2aSJeff Layton error = PTR_ERR(to); 42991da177e4SLinus Torvalds goto exit1; 430091a27b2aSJeff Layton } 43011da177e4SLinus Torvalds 43021da177e4SLinus Torvalds error = -EXDEV; 4303f5beed75SAl Viro if (old_path.mnt != new_path.mnt) 43041da177e4SLinus Torvalds goto exit2; 43051da177e4SLinus Torvalds 43061da177e4SLinus Torvalds error = -EBUSY; 4307f5beed75SAl Viro if (old_type != LAST_NORM) 43081da177e4SLinus Torvalds goto exit2; 43091da177e4SLinus Torvalds 43100a7c3937SMiklos Szeredi if (flags & RENAME_NOREPLACE) 43110a7c3937SMiklos Szeredi error = -EEXIST; 4312f5beed75SAl Viro if (new_type != LAST_NORM) 43131da177e4SLinus Torvalds goto exit2; 43141da177e4SLinus Torvalds 4315f5beed75SAl Viro error = mnt_want_write(old_path.mnt); 4316c30dabfeSJan Kara if (error) 4317c30dabfeSJan Kara goto exit2; 4318c30dabfeSJan Kara 43198e6d782cSJ. Bruce Fields retry_deleg: 4320f5beed75SAl Viro trap = lock_rename(new_path.dentry, old_path.dentry); 43211da177e4SLinus Torvalds 4322f5beed75SAl Viro old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags); 43231da177e4SLinus Torvalds error = PTR_ERR(old_dentry); 43241da177e4SLinus Torvalds if (IS_ERR(old_dentry)) 43251da177e4SLinus Torvalds goto exit3; 43261da177e4SLinus Torvalds /* source must exist */ 43271da177e4SLinus Torvalds error = -ENOENT; 4328b18825a7SDavid Howells if (d_is_negative(old_dentry)) 43291da177e4SLinus Torvalds goto exit4; 4330f5beed75SAl Viro new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags); 43311da177e4SLinus Torvalds error = PTR_ERR(new_dentry); 43321da177e4SLinus Torvalds if (IS_ERR(new_dentry)) 43331da177e4SLinus Torvalds goto exit4; 43340a7c3937SMiklos Szeredi error = -EEXIST; 43350a7c3937SMiklos Szeredi if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) 43360a7c3937SMiklos Szeredi goto exit5; 4337da1ce067SMiklos Szeredi if (flags & RENAME_EXCHANGE) { 4338da1ce067SMiklos Szeredi error = -ENOENT; 4339da1ce067SMiklos Szeredi if (d_is_negative(new_dentry)) 4340da1ce067SMiklos Szeredi goto exit5; 4341da1ce067SMiklos Szeredi 4342da1ce067SMiklos Szeredi if (!d_is_dir(new_dentry)) { 4343da1ce067SMiklos Szeredi error = -ENOTDIR; 4344f5beed75SAl Viro if (new_last.name[new_last.len]) 4345da1ce067SMiklos Szeredi goto exit5; 4346da1ce067SMiklos Szeredi } 4347da1ce067SMiklos Szeredi } 43480a7c3937SMiklos Szeredi /* unless the source is a directory trailing slashes give -ENOTDIR */ 43490a7c3937SMiklos Szeredi if (!d_is_dir(old_dentry)) { 43500a7c3937SMiklos Szeredi error = -ENOTDIR; 4351f5beed75SAl Viro if (old_last.name[old_last.len]) 43520a7c3937SMiklos Szeredi goto exit5; 4353f5beed75SAl Viro if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len]) 43540a7c3937SMiklos Szeredi goto exit5; 43550a7c3937SMiklos Szeredi } 43560a7c3937SMiklos Szeredi /* source should not be ancestor of target */ 43570a7c3937SMiklos Szeredi error = -EINVAL; 43580a7c3937SMiklos Szeredi if (old_dentry == trap) 43590a7c3937SMiklos Szeredi goto exit5; 43601da177e4SLinus Torvalds /* target should not be an ancestor of source */ 4361da1ce067SMiklos Szeredi if (!(flags & RENAME_EXCHANGE)) 43621da177e4SLinus Torvalds error = -ENOTEMPTY; 43631da177e4SLinus Torvalds if (new_dentry == trap) 43641da177e4SLinus Torvalds goto exit5; 43651da177e4SLinus Torvalds 4366f5beed75SAl Viro error = security_path_rename(&old_path, old_dentry, 4367f5beed75SAl Viro &new_path, new_dentry, flags); 4368be6d3e56SKentaro Takeda if (error) 4369c30dabfeSJan Kara goto exit5; 4370f5beed75SAl Viro error = vfs_rename(old_path.dentry->d_inode, old_dentry, 4371f5beed75SAl Viro new_path.dentry->d_inode, new_dentry, 4372520c8b16SMiklos Szeredi &delegated_inode, flags); 43731da177e4SLinus Torvalds exit5: 43741da177e4SLinus Torvalds dput(new_dentry); 43751da177e4SLinus Torvalds exit4: 43761da177e4SLinus Torvalds dput(old_dentry); 43771da177e4SLinus Torvalds exit3: 4378f5beed75SAl Viro unlock_rename(new_path.dentry, old_path.dentry); 43798e6d782cSJ. Bruce Fields if (delegated_inode) { 43808e6d782cSJ. Bruce Fields error = break_deleg_wait(&delegated_inode); 43818e6d782cSJ. Bruce Fields if (!error) 43828e6d782cSJ. Bruce Fields goto retry_deleg; 43838e6d782cSJ. Bruce Fields } 4384f5beed75SAl Viro mnt_drop_write(old_path.mnt); 43851da177e4SLinus Torvalds exit2: 4386c6a94284SJeff Layton if (retry_estale(error, lookup_flags)) 4387c6a94284SJeff Layton should_retry = true; 4388f5beed75SAl Viro path_put(&new_path); 43892ad94ae6SAl Viro putname(to); 43901da177e4SLinus Torvalds exit1: 4391f5beed75SAl Viro path_put(&old_path); 43921da177e4SLinus Torvalds putname(from); 4393c6a94284SJeff Layton if (should_retry) { 4394c6a94284SJeff Layton should_retry = false; 4395c6a94284SJeff Layton lookup_flags |= LOOKUP_REVAL; 4396c6a94284SJeff Layton goto retry; 4397c6a94284SJeff Layton } 43982ad94ae6SAl Viro exit: 43991da177e4SLinus Torvalds return error; 44001da177e4SLinus Torvalds } 44011da177e4SLinus Torvalds 4402520c8b16SMiklos Szeredi SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname, 4403520c8b16SMiklos Szeredi int, newdfd, const char __user *, newname) 4404520c8b16SMiklos Szeredi { 4405520c8b16SMiklos Szeredi return sys_renameat2(olddfd, oldname, newdfd, newname, 0); 4406520c8b16SMiklos Szeredi } 4407520c8b16SMiklos Szeredi 4408a26eab24SHeiko Carstens SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname) 44095590ff0dSUlrich Drepper { 4410520c8b16SMiklos Szeredi return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0); 44115590ff0dSUlrich Drepper } 44125590ff0dSUlrich Drepper 4413787fb6bcSMiklos Szeredi int vfs_whiteout(struct inode *dir, struct dentry *dentry) 4414787fb6bcSMiklos Szeredi { 4415787fb6bcSMiklos Szeredi int error = may_create(dir, dentry); 4416787fb6bcSMiklos Szeredi if (error) 4417787fb6bcSMiklos Szeredi return error; 4418787fb6bcSMiklos Szeredi 4419787fb6bcSMiklos Szeredi if (!dir->i_op->mknod) 4420787fb6bcSMiklos Szeredi return -EPERM; 4421787fb6bcSMiklos Szeredi 4422787fb6bcSMiklos Szeredi return dir->i_op->mknod(dir, dentry, 4423787fb6bcSMiklos Szeredi S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); 4424787fb6bcSMiklos Szeredi } 4425787fb6bcSMiklos Szeredi EXPORT_SYMBOL(vfs_whiteout); 4426787fb6bcSMiklos Szeredi 44275d826c84SAl Viro int readlink_copy(char __user *buffer, int buflen, const char *link) 44281da177e4SLinus Torvalds { 44295d826c84SAl Viro int len = PTR_ERR(link); 44301da177e4SLinus Torvalds if (IS_ERR(link)) 44311da177e4SLinus Torvalds goto out; 44321da177e4SLinus Torvalds 44331da177e4SLinus Torvalds len = strlen(link); 44341da177e4SLinus Torvalds if (len > (unsigned) buflen) 44351da177e4SLinus Torvalds len = buflen; 44361da177e4SLinus Torvalds if (copy_to_user(buffer, link, len)) 44371da177e4SLinus Torvalds len = -EFAULT; 44381da177e4SLinus Torvalds out: 44391da177e4SLinus Torvalds return len; 44401da177e4SLinus Torvalds } 44415d826c84SAl Viro EXPORT_SYMBOL(readlink_copy); 44421da177e4SLinus Torvalds 44431da177e4SLinus Torvalds /* 44441da177e4SLinus Torvalds * A helper for ->readlink(). This should be used *ONLY* for symlinks that 44451da177e4SLinus Torvalds * have ->follow_link() touching nd only in nd_set_link(). Using (or not 44461da177e4SLinus Torvalds * using) it for any given inode is up to filesystem. 44471da177e4SLinus Torvalds */ 44481da177e4SLinus Torvalds int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44491da177e4SLinus Torvalds { 4450cc314eefSLinus Torvalds void *cookie; 4451d4dee48bSAl Viro const char *link = dentry->d_inode->i_link; 4452694a1764SMarcin Slusarz int res; 4453cc314eefSLinus Torvalds 4454d4dee48bSAl Viro if (!link) { 4455d4dee48bSAl Viro link = dentry->d_inode->i_op->follow_link(dentry, &cookie, NULL); 4456680baacbSAl Viro if (IS_ERR(link)) 4457680baacbSAl Viro return PTR_ERR(link); 4458d4dee48bSAl Viro } 4459680baacbSAl Viro res = readlink_copy(buffer, buflen, link); 4460680baacbSAl Viro if (cookie && dentry->d_inode->i_op->put_link) 4461680baacbSAl Viro dentry->d_inode->i_op->put_link(dentry, cookie); 4462694a1764SMarcin Slusarz return res; 44631da177e4SLinus Torvalds } 44644d359507SAl Viro EXPORT_SYMBOL(generic_readlink); 44651da177e4SLinus Torvalds 44661da177e4SLinus Torvalds /* get the link contents into pagecache */ 44671da177e4SLinus Torvalds static char *page_getlink(struct dentry * dentry, struct page **ppage) 44681da177e4SLinus Torvalds { 4469ebd09abbSDuane Griffin char *kaddr; 44701da177e4SLinus Torvalds struct page *page; 44711da177e4SLinus Torvalds struct address_space *mapping = dentry->d_inode->i_mapping; 4472090d2b18SPekka Enberg page = read_mapping_page(mapping, 0, NULL); 44731da177e4SLinus Torvalds if (IS_ERR(page)) 44746fe6900eSNick Piggin return (char*)page; 44751da177e4SLinus Torvalds *ppage = page; 4476ebd09abbSDuane Griffin kaddr = kmap(page); 4477ebd09abbSDuane Griffin nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1); 4478ebd09abbSDuane Griffin return kaddr; 44791da177e4SLinus Torvalds } 44801da177e4SLinus Torvalds 44811da177e4SLinus Torvalds int page_readlink(struct dentry *dentry, char __user *buffer, int buflen) 44821da177e4SLinus Torvalds { 44831da177e4SLinus Torvalds struct page *page = NULL; 44845d826c84SAl Viro int res = readlink_copy(buffer, buflen, page_getlink(dentry, &page)); 44851da177e4SLinus Torvalds if (page) { 44861da177e4SLinus Torvalds kunmap(page); 44871da177e4SLinus Torvalds page_cache_release(page); 44881da177e4SLinus Torvalds } 44891da177e4SLinus Torvalds return res; 44901da177e4SLinus Torvalds } 44914d359507SAl Viro EXPORT_SYMBOL(page_readlink); 44921da177e4SLinus Torvalds 4493680baacbSAl Viro const char *page_follow_link_light(struct dentry *dentry, void **cookie, struct nameidata *nd) 44941da177e4SLinus Torvalds { 4495cc314eefSLinus Torvalds struct page *page = NULL; 4496680baacbSAl Viro char *res = page_getlink(dentry, &page); 4497680baacbSAl Viro if (!IS_ERR(res)) 4498680baacbSAl Viro *cookie = page; 4499680baacbSAl Viro return res; 45001da177e4SLinus Torvalds } 45014d359507SAl Viro EXPORT_SYMBOL(page_follow_link_light); 45021da177e4SLinus Torvalds 4503680baacbSAl Viro void page_put_link(struct dentry *dentry, void *cookie) 45041da177e4SLinus Torvalds { 4505cc314eefSLinus Torvalds struct page *page = cookie; 45061da177e4SLinus Torvalds kunmap(page); 45071da177e4SLinus Torvalds page_cache_release(page); 45081da177e4SLinus Torvalds } 45094d359507SAl Viro EXPORT_SYMBOL(page_put_link); 45101da177e4SLinus Torvalds 451154566b2cSNick Piggin /* 451254566b2cSNick Piggin * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS 451354566b2cSNick Piggin */ 451454566b2cSNick Piggin int __page_symlink(struct inode *inode, const char *symname, int len, int nofs) 45151da177e4SLinus Torvalds { 45161da177e4SLinus Torvalds struct address_space *mapping = inode->i_mapping; 45170adb25d2SKirill Korotaev struct page *page; 4518afddba49SNick Piggin void *fsdata; 4519beb497abSDmitriy Monakhov int err; 45201da177e4SLinus Torvalds char *kaddr; 452154566b2cSNick Piggin unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE; 452254566b2cSNick Piggin if (nofs) 452354566b2cSNick Piggin flags |= AOP_FLAG_NOFS; 45241da177e4SLinus Torvalds 45257e53cac4SNeilBrown retry: 4526afddba49SNick Piggin err = pagecache_write_begin(NULL, mapping, 0, len-1, 452754566b2cSNick Piggin flags, &page, &fsdata); 45281da177e4SLinus Torvalds if (err) 4529afddba49SNick Piggin goto fail; 4530afddba49SNick Piggin 4531e8e3c3d6SCong Wang kaddr = kmap_atomic(page); 45321da177e4SLinus Torvalds memcpy(kaddr, symname, len-1); 4533e8e3c3d6SCong Wang kunmap_atomic(kaddr); 4534afddba49SNick Piggin 4535afddba49SNick Piggin err = pagecache_write_end(NULL, mapping, 0, len-1, len-1, 4536afddba49SNick Piggin page, fsdata); 45371da177e4SLinus Torvalds if (err < 0) 45381da177e4SLinus Torvalds goto fail; 4539afddba49SNick Piggin if (err < len-1) 4540afddba49SNick Piggin goto retry; 4541afddba49SNick Piggin 45421da177e4SLinus Torvalds mark_inode_dirty(inode); 45431da177e4SLinus Torvalds return 0; 45441da177e4SLinus Torvalds fail: 45451da177e4SLinus Torvalds return err; 45461da177e4SLinus Torvalds } 45474d359507SAl Viro EXPORT_SYMBOL(__page_symlink); 45481da177e4SLinus Torvalds 45490adb25d2SKirill Korotaev int page_symlink(struct inode *inode, const char *symname, int len) 45500adb25d2SKirill Korotaev { 45510adb25d2SKirill Korotaev return __page_symlink(inode, symname, len, 455254566b2cSNick Piggin !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS)); 45530adb25d2SKirill Korotaev } 45544d359507SAl Viro EXPORT_SYMBOL(page_symlink); 45550adb25d2SKirill Korotaev 455692e1d5beSArjan van de Ven const struct inode_operations page_symlink_inode_operations = { 45571da177e4SLinus Torvalds .readlink = generic_readlink, 45581da177e4SLinus Torvalds .follow_link = page_follow_link_light, 45591da177e4SLinus Torvalds .put_link = page_put_link, 45601da177e4SLinus Torvalds }; 45611da177e4SLinus Torvalds EXPORT_SYMBOL(page_symlink_inode_operations); 4562